Perhaps it is the program directors and station managers who are to blame, and not the DJ's themselves. Face it, we live in a world of information, and the various styles of music are just outgrowths of this. There was no mass media, so Bluegrass music was able to evolve from a finite number of influences. We can also trace the roots of specialized music forms like blues, jazz and Cajun music, and see how they grew from the cultures that combined and mixed. But today, we have a lot of young musicians, but we hardly have a definable culture.
Regionalism barely exists any more.
And there is no way to know what music influences a young person today has been exposed to. There are so many TV channels, radio stations and other influences that there is a total explosion of hybrid and weirdly cross-pollinated music styles, and there are going to be a lot more before there are fewer. I have seen kids who appear to be a cross between Ricki Lee Jones and Patsy Cline. We see more and more young people who have been exposed randomly to things, and what they come up with is no less valid than what Bill Monroe did with the influences he had to work with. There are too many styles and artists.