In response to polar123's comment:
If the music industry has changed in the last twenty years, it may be due to technology-- the way we get our music. People that would not even see the insde of a music exec's waitiing room are the flavor of the month due to social media websites like YouTube and Facebook. The internet has changed the way we see and get our music, and learn about artists.. Good or bad, tons of music and information are now at the tip of your fingers, and if you like something, you send it along and it catches fire ala Rebbeca Black. Music executives are just taking advantage of this "trend." Wether or not the music is good, or watered down is really up to the listener imo. If something is good and unique, it will probably rise on its own merits like the Black Keys, Heartless Bastards, Lucinda Williams, and others as demonstrated by Yoga's above post.
To be honest the Justin Beibers of the world have always been around in the form of David Cassidy, and Bobby Sherman, singers who appeal more for their looks than actual talent. Nothing new there.
This is a piece to the pie, but it's not the whole pie.
I was addressing more what the root causes might be for the bottoming out of the quality of current music. You can only be judged and benchmarked against your competition. This is true in any industry -- think about going on an interview and having the sense that you had the job in the bag because you could address every bullet point and aced the interview --- not knowing that all of your competitors had similar high-quality resumes, and also aced their interviews, too. You still might get the job, but the high quality competition speaks for the candidate pool, and if you get the job, it's an honor and an achievement.
But what if, in another scenario, you and all the other candidates were thought to be fairly mediocre? What if the employer invited you and the others in because they didn't want to pay for a higher priced, more experienced person, and they decided to lower the bar and take a less qualified person so they could also lower the salary?
Your same resume would continue to take on a different value, depending on your competition, sometimes making it look golden, sometimes making it look merely gold-plated. :)
When competition is weak, is it as hard to be above the fray?
This is why there may be validity to the notion that we've had a long stretch of mediocre artists, who are made to look strong, because their competition is weak.
In the cases where the cream really does rise to the top (Keys, Bastards, Williams, etc. (though I don't like Williams ... hahaha) , they will will rise to the top anyhow --- but as previously discussed, it will take a lot longer because they came on the scene when the competition was more stringent or because they were not using a formula. Anyhow, just something to consider. =)