CoD4 =/= realism. Regenerating health, infinitley respawning enemies, and brown =/= realism. Frankly, I'm bored as hell of this "realistic" shit developers keep forcing down our throats, and I'm glad Infinity Ward putting some effort into making an environment that isn't either a dusty Iraqi city or a forest in the Ukraine. I thought the first Modern Warfare was quite bland and boring, and I'm actually hopeful for MW2.
Realism can be fun for a while, but when it gets ground down too much it gets boring, just like everything else that was once considered fresh and original; I'm sure I don't need to explain to anybody how overdone the World War II, Modern War, Space-Marine, and Zombie genres of FPS's have become. I'd rather play a game where I throw knives at people from the back of a snowmobile gunning through a castle set in a forest on the fricking moon before I'd play another drab, modern war game.
I believe this quote applies here:
"Some people like to make fantasy as realistic as possible. These people are boring. Avoid them."
That basically sums up my thoughts on the matter. Video games are, first and formost, supposed to be FUN. Realism will always take a backseat to this, even in super-realistic games like Brothers in Arms or the first three Rainbow Six games (as fun as it was, Vegas doesn't count as "realistic"); these games are great because they're fun, not because they're realistic. Some of the fun may be derived from realism, but that's not why they're good. Thankfully, Infinity Ward seems to have realized this, and because of this, I'm actually looking forward to a game that otherwise would have been a carbon-copy of the first Modern Warfare.