And we are already limiting the amount of realism by having the combat round 10-seconds long.
I like a certain level of realism in my games, like: up is up, blue in NOT green, and rocks are hard and can hurt you. But, for playability reasons, certain things have to be abstracted - not too much, mind you, but some. And, as has been mentioned a few times, the amount of heroism you want will help dictate certain aspects.