Not surprised at all. One could argue it was the API that attracted so many people to Twitter in the first place. It seemed really smart to me at first to create such a great ecosystem, but maybe there's more behind that scenes that I don't know about?
Either way it's sad to see this service go. The guy seems nice and provided a good service, but clearly he's not going to spend a bunch of his own time and money if it's not rewarding anymore.
I'm sure it would be but I think it would teach folks about Samba and mounting drives, it just scratches the surface of Samba but might get someone interested in building a real server with it.
The point of all these people doing "Raspberry Pi" articles with basic Linux stuff is to teach people who just bought a Pi and don't know how to use it. The overall point of this device is education.