This post is coming from a die-hard Bethesda fan. I have played all the games, including Redguard & Battlespire, and in Skyrim alone have logged 500 hours on several different characters. I say this just to let you know that I believe I have the perspective to make the comments I am about to. Even fans can and should offer constructive criticism (though not unconstructive things). These remarks generally apply to the mechanics or feel of the game, this is not a "bug" list. I will list some things first and expound: (the wall of text)

1. 2 handed spell system, while preventing "cheating" of casting spells with a sword and shield in your hand, still does not let a 1h weapon wielder & 1h spell caster block. Please just let us assign a block key if nothing else to attempt to fix this.
2. Spells (destruction) in vanilla Oblivion do not keep up with melee damage/dps
3. Levels. I'm a P&P player & DM for 25+ years.... I know all about levels.... but ... do we need them - are they antiquated - how do we get away from them?
4. (Opposite direction here from #3) Bring back stats Str, Dex etc. if we dont have them its harder to tell what character is better for what. The archtypes did make sense. Although I have played a jack of all trades as well as specialists.... usually a jack of all trades is followed by the phrase... master of none. Character building has always been important to RPG's
5. Open Lock Spell. No, my mage does not know how to pick locks but he can cast magic to open containers. Bring it back. Same with fly, levitate, mark & recall. Yes the arguments about being game breaking may apply, but your high level characters are all game breaking in their own way. A better point is: invisibility and muffle is a bit game breaking, the AI has no chance, why not flying as well. Make the enemy adjust and use ranged weapons.
6. If you can make an effect a potion effect, then it should be a spell effect. Im looking at you "weakness to x" ability. Some people like to play alchemists, some enchanters or casters.
7. Companion auto-equip & phantom invis. inventory - kill it. It is stupid. I would rather have an NPC with no weapons go pick one up than have stupid weapons appear and my NPC not equip what I want them to use. Who decided max damage or AC was the equipping criteria? I thought this was also a role-playing game. Maybe I want my follower to look cool in a nice set of armor that might not be the best one.
8. 1st person is a big part of immersion for me. Therefore, if you are going to make werewolves or vampires, let us play in those forms in 1st person. (this is a smaller objection - I can live with it)
9. 1 ring instead of 2 (1 on each hand) really? I thought 1 ring on each hand was a good comprimise... yes, I think we all think 10 rings (1 for each finger) is insane.
10. Although I think in general great strides were made in the illusion school, frenzy and other mind control spells seem to eventually get out-leveled. (even with appropriate perks) Make them work just as well as destruction end game... but hey, we know we cant push around everyone, even with 100 Illusion skill.
11. make Monk a viable class (ok so for the purposes of Skyrim) make unarmed viable.
12. Please for the love of god let us store our saves based on character name, not in one big list. I have 1900 saves (not counting back-up).... searching through them for the right character svcks.

I believe that is all the specific points I would like to object to. In general I have felt (as have others) that games have been dumbed down in general (for the masses) and that we see that progression in MW, Oblivion and now Skyrim. Yes the graphics are cool, yes finishing moves (for melee) are cool (jury still out on archery & magic due to the fact that the cut scene invariably makes my attack that should have killed something now miss and we go through it again...) Yes, I will even support less content with more detail rather than a ton of content with no detail (Daggerfall)... to that end I think Morrowind hit the nail on the head, and may well be Bethesda's magnum opus.

Finally, I can't say this enough, bring back puzzles. The puzzles in these games are getting progressively easier. In some dark dungeon, at the end of the long haul, I want to find a puzzle that I actually have to think about and may well drive me to save and sleep on it until I figure it out.

Bethesda is the last remaining bastion of huge, sandbox worlds you can adventure in and do your own thing. (In my mind, this makes their games better than a Mass Effect or DA2 because you dont get railroaded through the story or area. You decide what you want to do when. Yes I like the ME series but you still cant help but feel railroaded.) Bring back some of the magic of past games and the stuff listed above as well as adding new stuff if you feel you have to for todays market.

My 2 copper. (Ok, so that was like 2 platinum)

All in all, Bethesda, keep up the good work, I will buy TES 6 and anything after that, I will buy (and have bought all TES games and all Fallout games). Thank you for entertaining me for so many years.

p.s. regarding characters. Im not sure people would go along with this one, but I thought the SW d20 take on Hit Points was the best. your starting, 1st level HP were your HP, then everything else was vitality. A critical hit bypassed your "vitality" and went right to your HP, so high level characters could (and should) still die from an arrow in the eye/brain or some other nasty occurance. (Im sure I will get flamed for this one)