As someone who ran a video rental store for four years, I find this as amusing as hell. If that many parents objected to violent video-games then this wouldn't even be an issue. Instead, the amount of parents who have put a game back after I described the content is a tiny, tiny fraction of the total. Not only were most parents uninterested, a good number of them were borderline offended that I said anything at all. I especially tried to do sway parents away from GTA titles, but it usually had no effect. As it turns out, kids love GTA; it's one of those games that they all want to play because they have some idea that they aren't supposed to play it.
I can say with complete honesty that I had more parents worried about "witchcraft" movies like Harry Potter than about violent games or films. That's the culture in many places in America, only no one is worried about changing it until something bad happens, then they forget about it, or wait for someone else to do something.
Truthfully, I don't even believe playing violent video-games would have an effect on a healthy kid. It's only when they play for hours and hours that I would worry, and that in itself should indicate that the parents aren't doing their job. A couple of hours of Halo a day isn't going to twist anyone who isn't already twisted.
As my mom pointed out, she grew up watching westerns and pretty much everyone in her generation played "good guys vs. bad guys" and had pretend shoot-outs all the time. Video-games aren't really that much different.
