I would definitely argue that today's youth are growing up too fast. Whilst this may seem an over generalization let me first make it clear i am not speaking about every demographic of today's youth, but a majority that i have observed both on media such as television and in real life.
I was born in 1991 and as such grew up in the nineties and early 2000s, and even but ten years ago things were different. Kids used to be, well more like kids, and less like kids wishing to be adults at a young age. These days you see children as young as eight or nine with mobile phone, Mp3 players, et cetera, and only ten years ago the most a normal kid would have is Gameboy or Nintendo. I myself didn't have either of these, but i am by no means a typical case.
However having observed both on the media and in real life the changes in social trends in this decade, suffice it to say i verily believe kids are indeed growing up too fast. If you watch a show from the 1990s you see kids acting normally, in much the same way they do in The Secret Seven books or the William books or what have you, and indeed it seems only last decade that things really began to change.
I remember at school in the late nineties the children in my grade (3) discussing matters like sex in a joking fashion, semi innocent it might be termed, and other adult subjects. Even then things were changing for the worse.
These days you go outside and never see kids playing in the street any more, or hanging out at the park. These days it's the mall, the beach or playing World of Warcraft on the home PC. The outcast kids like the emos and scene kids listen to music. But none of this reminds you of an ordinary kid playing pirates or cowboys and indians now does it?
Take William Brown for example. He is an ordinary eleven year old boy in fictitious England in the 1900s. He plays with his good friends the outlaws in and around his village, playing all sorts of games and getting up to some trouble. Boys will be boys as such. Now imagine William returning with some new books entitled 'William Gets a Wii' or 'William Surfs the Net' or even 'William Makes a Facebook Account'. It's painfully obvious times have changed for the worse.
Watch a show like Hannah Montana. It's all about looking pretty, getting dates, music, being a celebrity. Compare this to say Janet or Barbara from the Secret Seven. These days kids are less innocent, more adult quicker, and devoid of many of the qualities found common in those of the past century. Shows like the Fairly OddParents show that kids these days would rather have a plastic action figure or playset than throw stones or have a fight with some friends or race model boats.
It seems commercialization was evident even in William Brown's day mind you, he had a taste for sweets and had an almost Eddy like mind in means of gaining what he wanted. Mind you Ed, Edd n Eddy are fairly ordinary kids, playing as they do in the suburban cul-de-sac in Peach Creek. But it would seem that even their time is gone.
So i argue that indeed kids are growing up too fast, and i would also say that this is not a good thing.