I agree with the person above.
I'm definitely getting the feeling that you believe you can put people in a box according to what game they play ^^. But you can't put me in a box ( I won't know whether I'm dead or not ^^) If people are really as easy to categorise as you think they are, there are no reasons for politicians to ever fail or advertisements not to work.
I'm not sure which side of the line I fall on this. On the one hand, despite being a student, there are very few "loud brash" games that really interest me (unless it happens to be fun as well, I've never been particularly confined to a genre or a style)
But then, I could say, class myself in the "grandparents" category if that style of game was more suited to me and then the ratings might still be useful.
(Or not, if the games I'm obsessed with at the moment are Final Fantasty VII, XII, Raw Vs Smackdown, Uncharted, PixelJunk Eden, Lego Indiana Jones and Valkyria Chronicles, yet I dislike Modern Warfare, Shadow Hearts: Covenant and Soul Caliber aren't I defying each category you would lump games into?)
In the end, it comes down to it being ridiculous to replace the rating system with this. The rating system is to help parents protect their children from content they want to avoid and this system doesn't help that.
I've noticed rating schemes have already gone down the "frikkin' awesome exploding eyeballs" route, but I think we're overthinking this. I want to see a number on a box and to be able to turn the box over and find out why.
If I want to find a game I like, I listen to reviews, watch trailers and talk to friends. Why would a rating system be better than that?