Except he isn't generating media buzz because only people who check out mma message boards know about it and those people or us are gonna watch that shit anyway.
The internet is a form of media, and I'd argue that the internet may be MMA's most popular form of media. All of the threads/articles and headlines posted about Diaz on any website get's a tonne of buzz and discussion, it's just how it works with Diaz, he unintentionally markets himself.
As far as the interviews/count down shows and press conferences etc, the UFC know how to market things, it's simple. "Nick Diaz doesn't care about interviews or press conferences, MMA's bad boy just wants to get in the cage and fight". All they have to do is take that kind of angle to sell Nick Diaz. The I don't give a fck attitude/bad boy persona in a celebrity/star is always going to generate a load of interest. People love that stuff, everyone loves a good villain.