Yes, as I kind of hinted at in my post, the main reason is that they don't want the stigma that is associated with file sharing.

Even though there is a lot of (social) legal sharing going on between users, the focus is always on illegal sharing. He has a point there, though I think it's a pity.

IMO it's not even that suited to piracy, as the deduplication means that they can find everyone that has a file! Torrents are way better for that.

The principles of dropship could be used for sharing photos, videos, public datasets, git-like source control, or even as building block for wiki-like distributed databases. The possibilities are endless when every file can be called up with just its hash.

There is a way around this. Charge the person sharing the file a certain amount of money after a certain bandwidth (rather than the person downloading the file). This would virtually prevent large scale piracy without preventing many other usages.