TP really wan't anymore mature than MM. It is simply rated T because the ESRB has changed its standards since 2000 (which is ****ing rediculous). WW likely would have gotten a T rating too, had it not been for all the cartoony graphics and such.

That said, the next zelda probably will be rated T as well. I'll probably be 17 by the time zelda wii is released though, so it could be M for all I care.