Hmm, I dunno man, they're kids. I don't have a problem with little kids listening to Bieber, that's what he's there for, and frankly I listened to some shitty stuff when I was young too. But, I also had The Beatles playing in my parents car all the time when I was young. While I couldn't fully appreciate it back then, because my head was so wrapped up in Big Fun Party Mix 3, when I grew older I could go back and love them all over again.
Plus, kids like what other kids like. Everyone is listening to Bieber right now, just like everyone was listening to The Jonas Brothers two years ago. But, no 8 year old is going to talk to his friends about The Beatles, he's going to talk about stuff he knows the other kids know about. But that doesn't mean no kids listen to it, it just means its safer for them to discuss popular modern music rather then music that maybe only they know about among their friends.