Stupid, stupid, and stupid. I'm 19, I play M rated games, and I let my slightly younger but still sensible little brother play them too. I'm responsible enough to not let the tiny pre-teen brother play. He doesn't even get to watch. I shouldn't be arrested for such a thing, and my brother can tell the difference between reality and fiction so he won't go shooting up the school or anything.
How about this. Some idiotic somebody goes to your house for whatever reason and finds an M rated game that you bought for yourself and you happen to have a kid. The kid never played the game, only you have. However, this super law abiding citizen will report you for buying this game for the kid and you'll be hauled off to jail. Nice, isn't it?
Politicians should stay out of our business and let the ratings system take care of things. Also, it's not as if movies and tv doesn't show us violence either. People just like to blame video games because it makes stupid parents feel better because they have something to blame (when they should be blaming themselves for not teaching the kid common sense.) Also for not realizing that the kid bought and snuck a weapon into the house somehow.
Edit: No, how about this genius idea. Just advertise what they play.com (no spaces) to every parent that actually gives a damn about what their kids play (and those who are too stupid to care that their kids are playing M rated games). It's basically "should-my-kid-be-playing-this-or-not for morons." Problem solved.