It's not that simple that you can simply say there is no more good music anymore. I have been around long enough to know that for any time period, there is good and bad. In the late 80's, we had Poison, Gerardo and Milli Vanilli. You can also make the argument that the mainstream has mostly been bad except for the small time period when Nirvana broke through. Commercial radio is the culprit and it will not got any better until every single person turns off the radio and goes satellite. Once people start tuning out in droves, the dollars will speak and maybe you will see more new artists, less repetition of songs, less mind-draining emo and hip-hop, and hopefully less overplayed 90's music.
Obviously the independent music will never get heavy play on radio, what really sucks is that there are still plenty of major-label rock releases that don't get the attention they deserve.