I think Ace-Of-Something is onto something with his post:
ace_of_something said:
You could say the same thing about Master Chief and Halo.
And same with Cheesebob:
Cheesebob said:
...Although bioshock didn't do this
Emphasis is placed on Character appearance when said character actually HAS character, or a persona. You have to remember that you aren't YOU in this game, you're this character.
Games like Bioshock that don't do this don't do it because you are NOT a persona. Well, you are but you aren't. You're a nameless, faceless protagonist. With Mirror's Edge and Halo, you're more taking on a character's set persona.
Does that make sense?