What am I missing? Why are people doing this? And what is this?
Technicall that's probably because what Flipmo said.
Also for fun, to do something people will like, showing the joy of being young etc.

To me it was a great show and personally I would love to be a part of something like this.
Just watching these videos makes me feel great.
It's somewhat like that video of a guy performing his fancy dance all over the world with local people.
edit: this:
[YOUTUBE]zlfKdbWwruY[/YOUTUBE]
I find things like these awesome and give huge props to people doing them.