I think the trend that young girls wanted to look older and act older exists through generations and we can recall child stars from every generation. These children of course appealed to their peers as identification of "this could be me - famous in the world" is the major part, not the beautifull covers they sing or the way they act.
In modern times getting famous seems to be the most important drive for a rapid growing group of teenagers - Idols and other TV programs, YouTube etc all create the imagination that it is a matter of luck and you are famous. I think in the past you were famous because you achieved something (usually through hard work), now you are famous if you are on television / the news (sometimes still through hard work, but there are many other tricks to reach the news)
Sounding like an old man I can say they way young girls behave is a result of our society and i am not too concerned about that, as long as the expectations from the children are realistic. The need to be famous worries me more, which costs these children so much energy that they could spend on nicer topics, like enjoying their life and friends.
