In order for a decentralized information network to take off it has to have a killer app other than the one that the activists like. Most people don't care about privacy in practice. They say that they do if you ask them but they won't do a damn thing to protect it. The same with freedom of speech.

In order for a technology to become mainstream there has to be an obvious, immediate benefit.

Piracy comes to mind, but the ISP's haven't cracked down enough yet for that to be a major enough issue.

Bandwidth caps could also be a prod, but I don't think people would be any more annoyed with those than the inevitably higher latency (between geographically disparate people) of a distributed network.

And then there's the bootstrapping problem.