Actually, it seems to me that ESRB ratings can to a certain extent determine whether a game is "good" or "bad". As far as I've seen, M-rated games are ALWAYS bad - they always have something gratuitously immoral in them. T-rated games can also frequently be bad, though in a lesser degree; SSBM and some others are exceptions. But I certainly don't look down on E-rated games; that would be insane.
Actually, one important reason for my dislike of the Xbox and PS2 is that some of the most popular and publicized games on those systems have bad or obnoxious stuff in them. Thus I have come to view those systems as more connected with the "dark side" of gaming than the GCN is. This is probably a big generalization (the GCN has "M" games too), but so many Xbox/PS2 fans say those systems are better because of "mature content" that I have trouble seeing the matter any other way.