What about controlled sharing? You may want to share something with someone and them only. Would you like others to see it? (Here others being the government). Sharing just doesn't always mean speaking out loud. It can also mean whispering to your friends. As social networking sites became the present day's trend, encrypting a mail and then sending it to attain privacy might look a heavy job. With diaspora, you can save that headache, when you attain privacy along with sharing. IMO, it's a double treat..