It's a player and developer friendly way to do health/damage etc. Few people give a fuck about realism.
Uh, isn't R6 supposed to be realistic? To force the player to plan their actions beforehand and proceed with caution? Last time I checked, you don't need tactics when you can just run through a level blasting terrorists left and right. In fact, you can't have tactics in R6: Vegas because the levels are completely scripted and there's no way to avoid being ambushed by terrorists popping out of random closets.
Calling R6: Vegas a tactical shooter is a joke. You might as well call Duke Nukem a tactical shooter. So yes, I give a fuck about realism, especially in a game that needs to be realistic.
Oh, and don't even get me started on the incredibly cheap cover system. Not only can you see enemies while you are perfectly safe behind cover but you can actually aim at them too. Amazing. You might as well just turn on God mode and autoaim.