If you play games like the Arma series they have a nice feature where you can move your characters head in almost any direction you want without compromising your mobility. This not only adds more realism but it enhances the gameplay experience as well. When I play games like BF3 I'm constantly finding myself frustrated that in order to look a direction I have to turn my entire body that direction just to see what's over there. It completely slows me down and makes me more vulnerable while I do that.
In games like BF3, if you had that option (which they do when youre driving a vehicle, mind you), if you turn your head and see someone chances are you're going to die quickly enough that you're going to have wish when you turned to look you just brought your gun with you.
Arma and BF3 are totally different games and to try to pull in factors from Arma for BF would just make BF less fun.