I'm personally of the opinion that music is music, its either good or bad, be it rock, jazz, classical or nose-flute.
There are crappy pop artists, and wonderful pop artists, there are crappy classical artists and wonderful classical artists.
for every Beethoven the classical world has seen it has had dozens of "paris hiltons" and other wannabes that have been forgotten since because they sucked. likewise, there are some horrible acts in pop music out there at the moment, mostly created to make a quick buck by large corporations, but we also have great songwriters like Carol King.
and that's true of every art form, look at painting, we see allot of old artists, but how many at any one time period and even less in a single region during a small time period, yet we look today and there are seemingly more painters than ever before, most of them are bad. Time forgets people who are not good in their field, so much so that after a while, it seems like there was a time that no bad could be done when in fact it was as bad as today, but history forgot the fluff and kept the important stuff.
unless I really try, I can't generally think of what crappy bands were "it" a few years ago, but I seem to never have trouble remembering those masterpieces, be it classical music jazz, pop or klingon drinking song.
it's okay for you to not like a certain style of music, every one of us does the same, what's not correct is to say that everything in that genre "minus a few exceptions" is bad, because thats true of EVERYTHING in art.
most classical music written is plain bad, but it doesn't survive the decades and centuries like the great stuff does so we don't see it as much.
but walk into any conservatory, musical academy etc, find where the composers nest, listen to the "great music" they are doing, most of it is garbage. the only reason they aren't being played on MTV is because they don't have enough money for breast implants or can't dance ... or both.
anyways... its 4am, im working in 3 hours, was trying to sleep and couldn't, although after writing this boring repetitive post, I'm thinking I'll be able to sleep :)