Why is modern pop music today so terrible?

A few years ago Billy Bob Thornton claimed that there was no great rock and roll produced after 1979.   Maybe he meant by any performers who began their careers after 1979.   I listen to Casey Kasem's top 40 re-runs from the 1970s on Sirius and though there was some mediocre pop music from that era there was also some great music.   I am disappointed in most contemporary music of all popular genres but people like Randy Newman and Paul Simon are still making new and quality music.

Just like pollution ,education,and music . People just do not know better

Blame the record companies ? 
They still make intelligent wonderful music that ignorant people don't buy.
 

Because it's recorded, mixed, and mastered to be played on the radio or a smart phone and cheap earbuds.  It is more often than not over-EQ'd and over-compressed.  Not meant for critical listening - background noise at best.

If you think pop just got bad lately then you didn't grow up with Yummy, Yummy, Yummy (I've got love in my tummy) - 1910 Fruitgum Company