On pc it's as simple as open the console and type showracemenu. Has done it with lots of characters, mainly because it took a long time learning the Oblvion face creator and I wanted to start the game not using a hour tweaking the character.
Xbox and PS3 players don't have that option.
Yes changing race or six might screw up starting attributes, spells / powers and relations, in fallout 3 it was purely cosmetic.
And no problem hiding the face change away like an Easter egg, visit a witch in a remote location, get her to like you or do a mini quest like giving her five grand soul gems to change appearance. You will not notice it unless you play the game for years or read a guide.
Console is a terrible example as the console is meant to debug for us modders, not to be used as a cheat tool which most PC players do. It's not meant to be used for playing the game. I don't like it going against the lore. At least easter eggs in the past have fit in the lore, this would not. I still don't see why people can't get it right the first time or start over if shortly after they start the game. I mean if you really played the game for hundreds of hours and you didn't have a problem with the looks before then you don't need to change them some other time.
No, it really doesnt need a precedent. They add things that have never been talked about in lore to the new games all the time. Again, your under estimating the ancients. They did nose jobs, facecelifts, even tummy tucks. Still, its a game. If they dont give us adequate lighting in character creation then yes, some sort of editor is required. It can take me hours to get a character right. Honestly, the only people that could be against this is A. people who dont care what their character looks like, so they think other people shouldnt either. Or B. Didnt know it was possible.
Yes it does need precedence and seeing as how morphing physiology has been talked about alot in lore and all of it was gods doing it (with the exception of the Ayleids) it pretty much says that it's impossible to do willy nilly. They aren't required to give you anything. If they wanted to make the character creation template pitch black where you had to guess what your character would look like, that's all they have to do. You act like your entitled to every little tiny feature that is trivial and not worth the time because your buying the game. All BGS owes you is a game that gives you $60 worth of gameplay which it will have way more than that worth, so they don't have to give you trivial little features when you can just drop your OCD and get it right the first time around. I don't see how you could get a character so wrong that when you go out in the light it looks hideous.
Maybe things change in 200 years, healers start doing such things, and that invokes the wrath of Alduin... Would be one lame storyline, but anyway.
Also, I'll reiterate again. We shouldn't warp the lore so that we can fit in some tiny, useless feature. The game should be molded to the lore not the other way around. People seem to think that 200 years makes such a big difference. The only period in time were 200 years made a significant difference was in the last 200 years. That is the only time in human history that 200 years had a significant effect, so "it being 200 years later" is not a good reason for something magically happening that hadn't happened in millenia since the dawn era.