You wouldn't ask if you lived in China. Though bittorrent traffic may need to be disguised.
Decentralising the internet is generally a great idea.
Then take a look at Freenet. :P
An interesting point here is that Wikipedia actually works in China, only some articles are censored. I tried to bypass this by typing https://www.wikipedia.org into the browser, but it loaded the http version regardless.
This is just one answer. You know how Wikipedia is always asking for donations (and rightfully so)? Part of those donations go to paying server cost.
Well, this cuts the server cost by decentralizing their content.
I don't think it is so much a question about why. More that is pretty cool idea.