greed is always some element. What the music business will try to do is just what any other industry does; find something/someone that a lot of people responded to positively, then milk the cash cow dry. [some] artists try to make it all about their music, but in the end that desire for money and fame can put quality music on the wayside, hence "sellouts".
Also, beast, if you're just listening to the mainstream hip-hop talking about money, bitches, etc, I might say I agree with you. But to say that ALL hip-hop should burn is ignorant, I must agree with violent in that respect. The old skool definitely had a message, and there are still rappers who "keep it real" out there, you just don't know them because you're apparently too close minded when it comes to music.