Actually, this is a pretty easy phenomena to explain:

13 - 15 are hitting puberty. biologically, they are able to reproduce and generally do what adults do, but they are still "not adults" for another 3 - 5 years. they don't know what responsibility is. They're forced to go to school, they don't have to pay their own bills, and if they do have a job, it generally is to pay their OWN expenses and then everything extra goes into buying whatever THEY want.

The only thing really that they can figure out that would prove that they are adults is wanting to do "adult only" activities, and refusing to do or like any "for kids" activities.

It's not until they actually have to be responsible, work at a lame ass job in order to cover bills for both them and whatever family they have, actually help their kids with homework or at least interact with their spouse/fiance/partner instead of just doing whatever they want, tht they realise "Oh, snap! THIS is what it means to be an adult?! I liked being a kid better!"

So in a nutshell, there you have it.

 I don't think scorn at the teletubbies counts. That's a gay show if I've ever seen one.

But Sesame Street is cool. A lot of kids TV shows really do suck, but older people like them for nostalgic reasons. For me it's stuff like Transformers or He-Man. Even though I am now old enough to realise that they are just 30 minute toy adverts, I still have a place in my heart for them. Sesame Street, on the other hand, is a genuinely worthy show. It is one of the few programmes in history that can claim to be both educational and entertaining for kids.

Jim Henson was a true visionary and pretty much everything he ever did is pure gold. 

@ Grey Acumen

Nail on head. Adulthood sux!!! 

When I was a 13- to 16-year-old, instead of distancing myself from the kiddy stuff, I distanced myself from the "new" kiddy stuff, and identified with the "good, old" kiddy stuff (as well as normal stuff).

I was advanced for my age. ;)