Why do people hate good pop music?

A lot of these, but not all, rock and metal fanatics just love to slam pop music whenever they can, when really pop is a good genre of music, it's just these terrible artists today that give it a bad name. And they also say Britney Spears was always awful. That's just not true, she did have a lot of talent, and it was shown in a lot of her old songs that weren't singles. But since she makes crap nowadays, they think that she always has been. The '90s was a good era for pop, but nowadays, it's just total crap, but people will say that pop has always sucked and they'll use today's songs as an example, when there are good songs out there. Plus, no genre is infallible; I have seen some pretty poor rock and metal bands.