Who's to say that their idol is necessarily less meaningful than anyone else's?
If they are basing on looks and dress sense at least they have made some aesthetic judgement.
To some older people, Bieber would seem far too girlish looking for their tastes, but that might say more about their own loss of innocence - and their materialistic attraction to those who look a bit more 'manly and providing' than it does about Bieber.
Sadly, for this reason, and through no particular fault of Bieber, he might only tend to attract mothering types in future- a bit like happened to Cliff Richard no matter how fit he keeps himself. That's the world. The innocent can never last. Not in Britain anyway unless you become counter-cultural against it and remain a true life-long Bieber fan - or whatever your equivalent of Bieber is. Hopefully one that's a bit more of a genius.
Jim Morrison perhaps.
I hate when 'academics' (probably some of you in the future) profess to like someone like Bieber as a 'guilty secret' as if academia and entertainment are intrinsically at odds with each other- as if the former is always about reason and the latter always about emotion.