The few times I've watched David Chapelle and Chris Rock, I thought they were funny. When you live in a ghetto, surrounded by people with a ghetto mentality, the same problems,etc. it's very hard to be different. That goes for just about everyone. When you want to be different and outside the 'mainstream' you pay the price.
Dave Chappelle's Show co-writer is a white dude, Neal Brennan. Dave and Neal met years ago and have been friends and co-writers ever since.
For those of you who have the Chappelle's Show DVD, make sure you watch some of the episodes with the audio commentary on. It will give you some interesting insight about the show and how it was written.