Artistic criticism is a valid and worthwhile endeavor. Done well, it gives us insight into our culture and the art that enriches our lives (or wastes our time). But you're right, what you have here is nothing more than a rant.
Taste is subjective and you can't argue that pop music or rap is inferior to "the metal, the jazz, the blues" that you prefer. Well, I guess you can make any argument you like, but it's not a very strong or compelling argument. It will very quickly decline into a shouting match with you on one side screaming, "rock rules!" and a bunch of Little Monsters on the other saying "GaGa's the greatest!"
As for me, I like all kinds of music. Social commentary rap from Kanye and Common and the Roots. Country artists Charlie Daniels, Johnny Cash, Lady Antebellum, and the Zac Brown Band. Shredders like Paul Gilbert and Joe Satriani. Singer-songwriters like Paul Simon and Bob Dylan. Bach and Chopin.
It's a big musical world out there and I can't imagine it without the dark, serious lo-fi recording of Bruce Springsteen's Nebraska
or the mindless, feel-good, party-all-the-time bubblegum-pop of Ke$ha's Animal
(one of my guilty pleasures.
What do you listen to when you want to get down, Buckethead and Michael Angelo Batio . . . or Marvin G a y e and Janet Jackson?