*1. A lot of times in many game series strict adherence to lore and logic, fictional or otherwise, is not conducive to fun gameplay. A compromise between gameplay and logic has to be reached, and more often than not it's the logic that takes the hit. If a person had to choose, I'm positive that person would rather play the fun game rather than the logical one.
And I maintain that gameplay and logic can coincide very well. It had been doing so quite nicely for past games.
2. Well...your whole scenario of someone hacking and slashing their way to the top of the Mage's Guild doesn't make very much sense to me. I mean, why would anyone join the Mage's Guild with no intent to use their magic skills?
And yet that's exactly what the completionist who can't stand the idea of requirements and factional consequence does. He starts out with one archetype character, finishes the most appropriate faction questline for that archetype, and then moves onto another one. In this case, it's the Mages Guild. Since it's a bore to raise those minor skills from the barest minimum to acceptable standards, he instead utilizes those skills he already has. And the funny thing is... There's absolutely nothing in the game to stop or even seriously discourage you to do that. The fact remains that you can just blaze your way through to the head of the Mages Guild without knowing a single thing about magic. It's not so much whether people will use that opening or not; it's the fact that the opening exists at all.
3. I think the Dark Brotherhood is a special exception. I mean, no character is going to openly identify themself as a professional assassin. They would probably have a day job in one of the other guilds as a cover. So I'm perfectly okay with being able to belong to an assassin guild and the more mundane ones with no major consequences.
And yet your character acquires infamy from their actions as a Dark Brotherhood agent. And while infamy is not something I agree with in the abstract, the concept it's exhibiting to the current example is valid. Even if you're the best assassin in the world, rumor is going to get around, some people are going to see things that, while mundane in and of themselves, put together with a sinister occurrence fosters the birth and potential spread of insinuations and inferences. In other words, after enough work in a faction of ill repute, people are going to have suspicions. Suspicions without proof will never get the law on your head, but suspicions certainly affect factional reactions. I'm not saying it has to be some big deal (the DB is a bit of a unique case), but it remains that consequences do exist.
*But a player isn't really earning anything by leading a guild. There are no real perks or compelling gameplay to be had at the top of a guild. It's just a title on a stat screen.
In terms of past games, not always. The Morag Tong in Morrowind had assassination writs that were reserved for the player becoming Grandmaster. IIRC, Daggerfall still had randomized quests that the heads of factions could experience. And it doesn't have to be the boring cut-and-dry way for the next game, either.
And besides, pretty much everything that the player aims for in these games that have game mechanics attached is just a title on a stat screen. Heading the guilds isn't unique in that. Why do you seek out money? To get better equipment? Why do you seek out better equipment? To better tackle challenges in the world. Why do you seek to tackle challenges in the world? To get high fame / to get high infamy / to rise to the head of X faction / to complete the MQ / to achieve this bounty / etc, etc, etc. Aside from personal unique character goals, everything in these games boils down to something on a stat menu. It doesn't change the fact that a sufficient amount of earning goes into attaining that title on a stat menu.
Bethesda's target market is anyone they think they might be able to con into buying their game. They're absolutely not just going to court RPG players. Especially with all the unwarranted grief they receive from them. If they think they can sell a game to someone, they'll certainly market it to them. I mean, just look at how Dragon Age is marketed. Especially the Sacred Ashes trailer. (I think that's what it's called) Absolutely nothing in that trailer resembles anything close to what it's like to actually play the game, but they market it the way they do in hopes that your average gamer will think it looks cool and buy it. It's a dirty business trying to appeal to as many people as possibe, knowing full well some on both sides will be disappointed, but that's what it takes to make enough money to keep making games.
That grab-who-you-can profit mentality can only remain stable and functional when they have a foundation from which to grab. You lose or cast aside the foundation, and then you either 1) painstakingly try to build up a new foundation out of bricks that hold no genre or title loyalty and are constantly scurrying about to other games, or 2) flounder, fail, and eventually collapse.
Perks, being able to upgrade skills e.g blade, blunt, archery, conjuration etc instead of having it like oblivion where skills increase over time;
Ick. Perks are gimmicky, especially in the context of a game that has natural skill-progression based on use. And I rather like that skill-progression based on use; it's characteristic of TES, it's unique, and it's far more believable than "You leveled up! Now pick from a contrived list of bonuses that have no relation whatsoever to what you've actually done to improve yourself, and inexplicably take place instantly and without cohesion.
Karma would be good, if you've got really good karma bandits, hghwaymen don't attack but villagers, knights, guards act really suspicious of you and blame you if someone gets killed near you but they say I'm holding you on suspicion of murder or something like that.
Double ick. Karma is just as bad as Fame/Infamy in that it portrays a universal morality system. And a universal morality system is not only completely unrealistic, unbelievable, and flawed, it's also boring as hell to boot. Why would I honestly believe that everyone in the world is going to look on my actions in the exact same light? Or even worse, that everyone's going to look at my actions through the polar extreme lenses of "supreme morality is good" or "it's good to be evil?" People have vast, varying, and numerous views of the world that cannot be captured with a blatant system of Good and Evil. Further, pre-Oblivion, TES has never had a universal morality system. It allowed the factions and people to judge you in a multitude of different ways based on the all-fairly-different concepts of what
they thought was right and wrong. Far more muddled, far more morally challenging, far more believable, and far more entertaining and fun.