I have never seen people complain about the Govenator firing an M-60 machine gun with one hand while shirtless:
http://www.youtube.com/watch?v=ix3EEipwRJk#t=6m12s
And damn if that scene didn't make that movie for some people (I know it did for me).
It's a video game, people. Let's indulge in a power fantasy why don't we?
And, you know, sometimes actual soldiers DO fight relatively exposed: