I agree that music can't be objectively good or bad. Let's put that aside.
There's lots of great music out there, but the most popular music is created by business people and increasingly, scientists, in the same way that McDonald's designs food items. Bad pop music is indistinguishable from fast food or nicotine or addictive drugs to the brain. No nutrition, but yet your lizard brain craves it. Now there are even brain scientists using fMRI machines to determine which sounds and chord progressions activate different parts of the brain. From a 2012 New Yorker article:
"Most of the songs played on Top Forty radio are collaborations between producers like Stargate and “top line†writers like Ester Dean. The producers compose the chord progressions, program the beats, and arrange the “synths,†or computer-made instrumental sounds; the top-liners come up with primary melodies, lyrics, and the all-important hooks, the ear-friendly musical phrases that lock you into the song. “It’s not enough to have one hook anymore,†Jay Brown, the president of Roc Nation, and Dean’s manager, told me recently. “You’ve got to have a hook in the intro, a hook in the pre-chorus, a hook in the chorus, and a hook in the bridge.†The reason, he explained, is that “people on average give a song seven seconds on the radio before they change the channel, and you got to hook them.â€
I don't eat fast food, but I get my Cheetos on now and again. But our nation is no sooner going to eschew pop music for more complicated, soulful music than it is going to give up fast food en masse. I see Pandora and Spotify as similar services to the local farm that brings a box of organic veggies to my house every week - I don't have to think about it and I know it will be good. So what do I care if my neighbor eats McDonald's and considers Autotune an expression of artistic talent.