There just might not be that high a quality of Hip-Hop now as there was "then."
Cue: "You sound old" retort. ;D
Fact is...Hip Hop used to have something to say. It was a message from the streets. Sort of a variation on what Punk was back in the 70's. The people listening could empathize with the stories told. I guess the easiest way to put it is:
Hip Hop went Hollywood.
The masses can't identify with the rich-penthouse-dwelling-superstar. When Hip Hop was at its best, it was street. And not some faux-thug talking about how he capped someone. The quality Hip Hop had credibility. The newer stuff comes across as homogenized and textbook. Yeah, that's it. The good Hip Hop wrote the textbook that the new generation is reading from. And you can't learn music from a book. It has to be real. And that's universal across all genres.
So, I guess what I'm really trying to say is: If the music were good enough, there would be a demand, and radio would react.
That's the formula. Give 'em what they want. And right now, there's no groundbreaking Hip Hop exciting the masses at a level tangible enough for radio to react.
...or I could be wrong.
...Burn Hollywood Burn!