First of all, I think it ain't matter if you played 10minutes or 10 years of the game, from the moment you fall in love with it, then consider yourself a fan.
And about the "face problem", I think people are trying to say something like, everybody has their own master chief in their hearts, different ways of smart and bravery, 117 is a different hero for everyone who loved this series, because of this, it somewhat affects how a master chief should look like in players hearts, like you wouldn't want to portrayed master chief as Indian or Asian or black or even a Caucasian, from the modelling wise, it won't fit no matter how you put it, from this point I can just say from past 9years of play, I got a pretty good icon deep down my heart that tell me exactly how master chief is looks like, and now halo4, at the end I felt a bit stranger kinda feeling, "is this 117? What happened to the chief?" These sorta feelings.
Master chief, he can reflect ourselves, if so, how can you put somebody else's face to him and without being awkward and complains? I don't care if he is in his world is fat old y'all short white black or Asian, as long as I don't know it, as long as he is my master chief, I don't care all that.
Halo famous for masked chief, it will stay famous because of the masked chief