It's interesting that even with gamer tags, it gives a personal quality to your player character. It makes that character into sort of an avatar when you are playing Halo or Black Ops. Would it make the game less personal if you couldn't have a gamer tag?
I feel like it would, yeah. It's kind of the same thing with avatars, except you take a more direct role. Also, if you couldn't have gamertags like "Steve has ED" or "Titty Bears" (which, if you were wondering, are both actual gamertags my roommate had), you take away the fun in coming up with new ones.
My gamer tag is Hanzo100