Dudes, you can't judge a genre based on what you've heard on the radio or TV. Radio music sucks monkey doo mostly. Seriously, check out Phi Life Cypher, Fort Minor, Styles of Beyond, Mos Def, and lots of other underground/alternative rap artists, along with some more popular MCs like Jay-Z and Eminem, and you'll find a treasure trove of great music that'll never appear on the radio. Rap isn't all booty, guns and grills, and it pains me to see people continue to assume it is.
And MC Hammer has never contributed anything to society, I'm sorry.