I think music sure has changed and the industry has changed plenty. But the assumption that mainstream music today is of less quality than previously is false straight up.
http://www.bbc.co.uk/radio1/chart/singles
Todays singles chart. It's a real mix of good songs, and bad songs. Cursory glance will reveal that Adele for example is 20 places higher than Nicki Minaj.
My point is, there's a lot of crap in the mainstream shelf, but there is also a HUGE increase in niche, underground and obscure music due to lower production costs. You don't need radio, you have webradio. You don't need to find new music. Last.fm, blogs, forums, spotify and itunes does it for you. And so forth.