Rock music is (depending what sort we're talking about at least) probably one of the most interesting and thought-provoking genres out there. A lot of rock bands talk about politics and (realistic) sex and angst and being part of the unglamorous working class, things that teens can relate to and want to know more about. To be honest, what's the alternative? Pop music where children are brainwashed and taught that if you're not pretty and rich, no one will care? Nonetheless, just let kids listen what they want to.