I was watching the latest trailer for Dishonored on gt.com and at one point the video turned into a macabre spectacle where the main character would be shown slitting the throats of his victims over and over and over. And it's not just this. Most games out there focus on killing human beings (virtual as they are). Why so much death? I don't think there is a single person out there that wants to die. So why remind ourselves of something that comes for each and everyone of us? The whole point of video games should be to forget that we are all going to die at one point or another and simply have fun.
Another point would be that games like Call of Duty sell by the billions because people like to murder other people, but can't in the real world as they are too afraid.