I want to see a game where there is a cover system, but you stay in first person so you can't see everything that is going around in the battlefield. In real life you pretty much sacrifice vision for not getting your face shot off, so I'd like to see that reflected into games.
There's also the way suppression works, as far as I've seen. When the other guy is shooting, you can't stick your head up and shoot at him or see where he is without being shot. Suppressing fire doesn't really work if everyone can see what's going regardless of the fact that their head is being kept down.