Well, since it is a game, it is difficult to make the argument that there is any real morality to be sacrificed. Though, I do see your point.
As for me, if things get really violent, I tend to prefer over-the-top portrayals, meaning that no one could possibly take what is going on seriously, and the whole thing becomes a satire of reality, more or less like Saint's Row. My problem comes when games have a pretension to gritty 'realism,' which is silly in the first place, but becomes much more distasteful when the actions taken by the characters show no real thought or restraint. The characters become totally unbelievable under these circumstances, and I begin to dislike them, ruining the fun.
Note that I then dislike the game more for poor characterization than for moral reasons.
That said, I do enjoy a good moral tale, where characters struggle to make the right choices, but those types of games usually fall more into a narrative-type of game rather than a sandbox-type.