This is a good question that I think every teenager should start answering for themselves. Because if teens keep following their parents' standards without any real convictions for themselves, what will happen? My guess: Once the parents let their children make their own decisions, they will flail. Suddenly, they might find themselves on a slippery slope with music and media. How could they not if they never really had any of their own convictions.
A verse sticks out in my mind about this.