I guess all pop music has been dumbed down. I mean, it's not like it was stellar 5 or even 10 years ago, but it was better. I think part of the reason is that the culture of American youth is also getting dumbed down on average. The society is going through a cultural recess, dumbing down their entertainment. hobbies and culture. That's at least my experience.
But there's still lots of quality music coming out though. There's lots of people liking more ambitious music, probably more than ever because of the popular music getting crappier.