@Sqrl: I can see what you mean, you're saying that those people who decide what rating each game will have, has too much power. I don't know who rates in ESBR, but game publishers rate their games themselves in PEGI. If they give rating which is too low, it will be changed (only game i recall which rating has been changed was GTA:SA, from 16+ to 18+) and every country can give the game own rating or even ban the game. Usually rating is checked if people complain about the content being at the level the rating says. Anyway, since ESRB gives the US rating, you would think that it's not very clever to not being fair when giving the rating, think about the possible multi-billion lawsuits.
At the moment it may be bad parenting if kids get their hands on games meant for mature audience, but without ratings, non-gaming parents wouldn't have anything from which they would know that will the game fit for their kids. Of course you can check that what kind of game a certain game is, but you really do have to do a lot of research, since previews usually doesn't have the amount of non-appropriate content reviewed.
Also, without ratings, the games industry, as it is at the moment, would be dead since games would a)have a reputation of violence etc. (just like J. Thompson would like) b)all be for everyone so that parents could buy games for "hardcore gamers".
@JustBen: I was being a little sarcastic, no other country bans as much games as Germany.
@Hus: As a gaming site, VGChartz seems to have surprisingly high age average. Most of this "older" people don't see violence "cool", just only as a stuff that kids must have since they think it's mature (like the games rating). Also this people have kids and have started to think something else than their own asses. A lot of games do have a lot of content, which us parents don't want our kids to see.