As a native Angeleno, I have yet to hear a black-oriented radio station that has ever deviated from complete "mainstream" programming in its playlist.
The only station that came closest to variety in its programming was the now-defunct radio station KUTE ("The Quiet Storm")--which played songs by Joan Armatrading, Third World and Whitney Houston as part of their format. But after about three years and low ratings, KUTE, as we knew it, was taken off the air.
The bottom line is . . . as consumers, we must take a stand, and demand of radio programmers the music we want to hear.