And just how long will it be before someone decides to create a WWG application that uses it as one vast storage pool of copyrighted material with distributed indexing of the contents and the RIAA, MPAA, ... of the world sue the whole thing into non-existance or buy laws to make it a criminal offence to run it?

Structured correctly you wouldn't know who was adding to it or downloading data from it. After all a download would be just be a request to replicate a bit more data making a vastly distributed virtual filesystem a bit more redundant. You may not even be able to tell if it was someone making a request to make a local copy or the software automatically increasing storage redundancy of static data (assuming that there's no logging).