Once again, there's a fine line to walk. The developers can have both options available to the player (something that it should be, considering "hardcoe mode"). Personally I wouldn't want hyper-realism, I just don't want the ridiculous cartoony-like empty-two-magazines-in-man's-face before he dies.
Difficulty shouldn't make every enemy into a bullet-sponge. Having an enemy sustaining several clips to the head isn't "difficulty", it's annoying and tedious. Fallout 3 did this.
I never want to see that bullet sponge crap they did in Fallout 3 either.
But I don't want a instakills.
So if they find a good ground between them both then I'm going to be a happy little schoolgirl.

But what I really would want is for the to create another mode called Realism Mode where it's realistic damage all around from both sides.
That way people who want it can get it and us who don't want it can just stick to Casual or hardcoe mode.