When I was 15, there was no internet, no cable TV, no satellite TV, terrestrial TV with its self censorship kept some sort of perspective I think. Now kids of 15 have access to information and propaganda that we couldn't get our hands on at 15...its a different world Phantom.
When we were kids, we would want to play the white hats, the good guys who win at the end. Today, kids want to be the gangstas...
Another reason I think are parents. When I was 15, my mom didn't work (well she did but not full time) so she was around to keep an eye on me. Today both parents work and kids aren't just under their parents' eye anymore and many parents just don't have a clue how their kids entertain themselves and well the internet is just beyond some of them.