In the Eighties I remember one of my first records was Queen's
" A night at the opera" and I was listening to it , my Dad came in and told me I shouldn't be listening to this crap and it would be forgotten , why not listen to the Beatles because lots of people like them so they where better.
I think its impossible to get rid of talent, and there will always be those with it. They might not play what we like but music gods will always be around and follow their path.
As for Rihanna she might be great, or not, time will tell, as far as I know Tom Jones never wrote a song but 40 years later we all know him.
I suppose u can put Heavy Metal with Rap and most of the Electro music, its fiercely followed and loved by a few,dismissed by the majority. But to say musically there is nothing there, to me is putting your head in the sand.
Money and Greed will always be the motivator for the music business so a lot of stuff sold will be copies of what makes it, and even worse replays of bands 20-30 years old because the 40-50 have all the money. We all want to relive our childhood.