My radio-listening time is confined to the 10 minutes it takes me to get to and from work and it's always NPR/Classical music. BUT, if we're going to talk about what's popular, we have to look at the impact of payola.
BET UnCut has made some people millionaires. Because they don't have to give a chunk of profits to large record labels, one (in)famous song can put a whole lotta change in their pocket.
Even beyond the UnCut crowd, there's always been a place for nonsense on the radio. Anybody remember Hammer's ummm "hammer" in that "Pumps and A Bump" video? 2 Live Crew/Luther Campbell? The "problem" is that these kinds of songs are 95% of what's being pushed.