I think the missing elements are fairly clear and Fallout 4 would do well to address them in the next installment to at the very least keep pace with the competition.
Travel: Given how advanced civilation had gotten and how well and long so many other major technologies survived, you would think one of the oldest in some form or another would make an appearance. Humans have not used foot transportation solely in over 6000 years. We have had and used boats, ships, horses, camels, elephants, dogs, automobiles, trains, airplanes, balloons, wind skimmers, skateboards, submarines, and spacecraft and many other forms not mentioned. It would be nice to see some vehicles stil working or at least some form of boat which is one of the most basic and oldest forms of transportation. It would also do nicely even to see some form of perhaps mutated animal take over the role of horses in this post apocolyptic world.
Locations: Since it is mentioned frequently as a nemesis, one possible location for Fallout 4 might be China, or at least Vladivostok Russia (since they are huge fans) with some locations across the border in China. This would be a very compelling location to hit upon both major powers in light of the aftermath. If Russia, is kept as a location then other good choices would be, Moscow with it's huge and recognozable Monuments, St. Petersburg, or the Crimea. London, Tokyo, Paris, or Berlin would also make nice locations but much less likely. In the US, I would prefer to see something in the middle or the south since the East and Western Coast areas have already been hit upon with California in part 1, and Vegas, and now Washington, so the Mid west or say Texas or New Orleans in the south should logically get a treatment next if in the US.
Weapons: The weapons are for the most part great though some are somewhat illogical or are too easily edged out by similar but better weapons. What is missing in the weapons area are good scope views when using weapons especially on zoom. There is simply no iron sights or gun sights varieties in the game what so ever with the exception of zoom scopes for sniper oriented weapons. This could well do with some improvements. It might even be prudent to have different looks or effects in the V.A.T.S. modes for different weapons or at the very least, different modes or looks and functions for different types of weapons such as big guns and melee classes. One weapon that does not make much sense to me is the 10MM pistol. A 9MM pistol is pretty powerful yet in this game that is such a comparatively weak weapon. Some things do not make sense why they weigh what they do or why no ammunition has weight.
Miscellaneous: Fast travel would make more sense if the player character had some form of transportation. It would be a nice add on element to have some vehical or pack animal or wagon to carry loot at least until you got home. Plus it would make sense. Technically you can carry way too much but only suffer moving slower. Another nice option to potentionally have is senses for say what may be important to keep. Inventory often proves problematic. You can not pick things you want to save or hold on to so that you do not accidentally drop it, sell it, or lose it. Such a option would be welcome and help manage the game better. While, I would not per say want or need a precise list of things that maybe important, it would at least be nice to know if there is a chance something is useful or if there is no chance whatsoever so that players do not sell things they may need later so easily. This is a bit clunky in game as it is since not everything that would seem useful say in real life is something the player character can interact with. Walls are not destructable, not every desk or cabinet can be opened, sometimes there are items where there is no logical reason even with the after math of nuclear blasts they should be (LOL), and sometimes important items like notes look too much like the textured garbage patterns on the floors or desks (in such cases you can not even tell if it is something actually on the desk or just some crap burned into it or part of the funky floor pattern), and in some cases even on a fairly light setting, everything is too dark to see anything that you would be able to pick up and then use. Items of importance should not really look so indistinguishable from the very floor patterns or be so dark you can not see it. If it were for real, you could at least feel or sense if soemthing was close to you even in the dark, so the game might do well to not be so much less sensory interactive than real life since often the player character is in fact supposed to be a bit more capable than a average human in the present world, and likewise, if it were real, there is little chance you would not be able to tell say even a sheet of paper from the carpeting or tile on the floor or the marks on a wall.
Companions: It would be nice to have more companion choices and even allow players to have more than the standard 3 or 4 member parties like every other rpg type game ever made with a very few exceptions. I can only think of one that allowed more than 4 party members and sort of broke the mold but none since and that was over 10 years ago. It is odd how it is so easy to get a evil karma companion and so early on versus good or neutral, at least in one of the games. Conservatively it is tough to leave the vault in one game without having good karma since some of the evil choices actually prove to be so negatively impacting on game progress (such as having no options to say convince an overseer, or possibly lose a companion option). These are a bit too wide affecting options to appear so early in the game. Not that I am evil but, if you pick the more evil option of killing the overseer in 3, then you do not get 2 or 3 options later in the game as you would if you chose the good option. There honestly should be another and very different evil option to resolve that later choice with the new overseer later. In fact, any such choices in game that have such profound impacts upon the game and story should have at least 3 options, and probably 3 options for each so that it can be twisted back at least for part of the choice path. This is more important early on in a game when such choices effect the game so much later on and can sadly severely limit choices.
Romance: Yes, the games have suggested more than common communication but nothing more, not even anything more really implied. Sleeping fully clothed in the same bed as Nova for example is not the same as some interlude implied. No, however, I am not saying this is make or break but to so vaguely imply something like that but yet be too scared to go more than what amounts to '50s tv shows couples sleeping in separate bunk beds, is not the way to go the extreme opposite of that either. There is no question this game is already well intended for advlts with the extreme graphic violence inherit in enemy death scenes so there is really no reason to at least have more than a very very G rated vaguely implied romantic interlude either. You could well give more rpg oriented options for anywhere from a one night stand to a marriage and family and really make the game seem like a real living breathing world. Technically this is already implied in the game but it is so bland and mild it is fodder for ridicule and a throw back to the very time period the game seems to center around.
Game/world Logic: There were many examples of MISSES in past games such as "Little Lamplight" and the mysterious unexplained way that the residents either never aged in the 200 years since the caves were collasped and the occupants more or less sealed at least for a time, or how they were miraculously replenished. This is sort of broken logic is illustrated in other ways as well. Things such as it is implied 200 years have passed and yet it is as if the war just happened a month or so ago. The timeline is a bit misleading. So many things suggest that the war took place in 2077 yet lots of evidence inexplicably connect the time line to have actually stopped between 1955 and 1965. I understand the alternate world here evolved differently but does not the world evolve at all? While I am not looking for precision potentially game breaking logic or history or reasoning to explain all of the minute details how this mysterious laspe in continuity of time occurred, it would at least be nice to have some hint, suggestion, or semblance of what and how it happened. The problem is, is that within the game it seems to skip events as though we should understand it or that it seemingly links events from the 50s and 60s directly to events in the 21st century as if little time had passed at all. In the end, there is very little history within the story suggested between 1965 ish to 2077ish. Examples of this strange time logic are seen in Vault 108 how Gary somehow survived so long in such a destroyed vault with what amounts to little food or resources or how the folk that went mad in 106 are still there at all mad or not. It is 200 years later? The gas should have run out by now if it was being released for that long and had enough volume to affect the residents so how is it explained they are either still there or somehow became temporarily civilized enough to reproduce? Another comical note about 106 is that, I never seen any females and many of the residents looked like one another. This is not bad in and of itself but, it is worse and more noticeable when they are standing side by side, LOL. These two examples also illustrate how the sense of time does not bear out very well within the timeline of the game and its story and history.
Still other examples do not correspond well to the implied story, rules, and theme of the game world/story. Why is it constantly said that supermutants do not kill but capture? Yet they never try to capture you? Though it is implied here at least that since you were not born in the vaults you are not a prime target, how do the supermutants know that before hand, especially since you lived in a vault? The same goes for the slavers. I never have seen them out attacking or trying to capture anyone let alone the player character. Which leads me to this category...
Alternate paths/Endings: If the game makers want to imply there is more than just hack and slash shoot and kill motives in the game such as captured by slavers or captured by supermutants and changed then should they not include some alternate story paths in the game to explore those alternate paths?
Path one: Captured by slavers, so you are captured and a collar put on you. Maybe you are forced to do say, quests related to becoming trained or a slave. This way you gain trust of either your slaver or later your owner and can either trick your way back to freedom, or be more devious and aggressive about it. Maybe brotherhood raids that slaver camp, or a merchant you help buys and frees you and maybe even you owe him or her money in return and or perhaps another side quest. Maybe, your owner or the slavers are killed by creatures on the way back to whatever home or camp they had and you hide until the animals are mutually killed or they leave or maybe you wait and get the keys or get a weapon and finish off the attackers then get the keys. There are so many ways that side plot alone could be explored and at the same time add many new side quests (possibly repeateable ones since you can be recaptured by others), that it would add so much to the game and possible range of choices your story can go.
Path two: Captured by supermutants. Though in some cases the player character may not be able to be turned, it is unlikely that all player characters in all Fallout games would share this theme as that would become mundane and boring. So perhaps you are captured, again there are options to escape, earn trust, side quests, and perhaps let us say you are transformed, maybe you become like Leo or Fawkes, and maybe even if you are transformed there is hope for a cure, more so perhaps if it is within a short time frame of your character's transformation. So again there are many paths here. You could have side quests perhaps as a transformed supermutant to either earn supermutant trust or find a cure or someone who knows it or has it. In these side quests, the normal supermutant faction enemies could be temporarily at least, your companions. Think of the richness of the story the game would take in just this side path alone?
Media: Other much older games have more options and range of in game media such as newspapers, books, movies, tv shows, radio shows, or music. Though I am not one to be overly bugged about this, it seems a bit of a let down to hear the same radio bits or music loop and replay over and over again on every channel because the range and selections are so limited. Could not a game this new with such up to date capacity do at least as well or better than older games?
In game Graphics: I am a bit curious why when you zoom into first person you only see floating hands. You never see your own body not even if you are knocked down or sit or get up or look down. Yet again, this sort of thing can be seen in older games and other such media. You can never spin around to see yourself from all angles in 3rd person view either which is a bit clunky too because then you can not see how different outfits look since there are not even any working mirrors. This sounds humorous. There are no working mirrors. Is it logical all mirrors would be smashed? And more so, even if all mirrors are smashed that you could still not see yourself in windows or the fragments of mirrors or even in the reflections of water?
To the person that mentioned interaction with other factions above, that is a good idea. I know there was a game that came out in the early 1990s that actually did have some faction interaction of sorts, in that you could fight with allies sometimes for mutual benefit. It would be pretty cool to have some instances of such a thing here. I have seen that it does on occasion hint at such a thing like when you come across the Brotherhood knights near GNR and then proceed to fight the first Behemoth. How cool would it be that if you befriended say the vamps, Rivet City, Brotherhood, Dave, and other settlements and factions and could call upon some reinforcements or fight a mutual big battle as allies and as part of some mass fight scene in game. I am not speaking from totally unproven perspectives. There have been very good rpg games that did in fact have such things and were lots of fun. They explored things from a variety of game play styles and modes into one such as flying a space ship and being in ship battles one moment, on your own in exploration rpg with deep story themes another, with a small party squad another, in a battle on foot with lots of allied troops another, or on vehicles or boats another.