Skar,
I like your answer to SE. I hadn't thought of that, but it is very rational. In addition, here's another thought on the matter.
How often, really, do these books encourage murder? I have violence in my books, but I sincerely don't see myself as encouraging murder.
Violence CAN represent senseless brutality. However, it can also be a powerful metaphor for the struggles we all must make--struggles of control, and battles of good vs. evil. So, when the hero fights off the evil doers, protecting the innocent, then goes and sleeps with his sexy sidekick, I find the second far worse. In the first case, I think he's done what he was supposed to--he may have had to kill, but few heroes are presented as LIKING that part of their job. The immorality, however, is presented as equally cool, but without the situational justification.
That's why I'm perfectly alright with video games that have an 'M' rating because you have to fight off an alien invasion, while disgusted by games with the same rating that have you carjacking, whoring, and creating general mayhem.