Why can't some people except a new generation of music?

Now I was born in '94 and I grew up listening to Jay-Z,Mya,Diddy[Puff Daddy],Biggie,Tupac,Eminem to Backstreet Boys&NSYNC and Britney.Honestly I didn't judge it at all I loved every type of music except country. Now I'm into Drake, Lil Wayne, Jonas Brothers, Hey Monday, paramore, Miley, Demi, Trey Songz, Rihanna, Ke$ha, and The Black Keys. I feel like everytime I open my mouth and talk about the Jonas Brothers they'll just quickly say "Oh they SUCK"and "listen to some real music like Metalica & ACDC".I just have to wonder WHY?!To me all music is the same and it doesnt matter what they talk about as long as sounds come out sounds come out.Plus they don't wanna target themselves as "Disney kids" or think of themselves as teen idols.