In theory, I would think of it as a good idea. However, when you become between the ages of 15 to 17 for example -18 being the legal age to drink alcohol in mainland Europe-, going to a club and dancing isn't exactly enough. From personal experiance and observation, teens around that age will obtain alcohol beforehand and go to the club having already drank for example. I would support the idea had there not been so many loopholes.
You might say I'm being cynical or I'm assuming that this happens with everyone, but it's quite true that drinking underage happens quite a lot. Due to the media and moderisation of our culture, going to a club even an under-age one promotes nightlife and eventually teens will be bored of just going to a club to dance and meet other people, it'll eventually start getting more serious.
I would like to see a way in which it could function, if it were legal to test alchol levels before entry or something like that it might work, as there's always bound to be someone who's had a few drinks in anticipation. From what I've seen of my friends and people around me, if they want to go to a club they'll go anyway, of course it's against the law but when you're 16, the law isn't going to stop you from drinking or going out if you can get away with it. Eh, as I say, it'd be nice to see a functional teen club organisation, it'd be a good way to socialize but due to the major accessabilty to drink and other narcotics, as well as the attitude of a lot of teens these days, it'd be a suprise to see it functioning.