Public: bad for you, good for everyone else.

I was thinking about a service that lets you add notes to books last night. My first thought was that every note had to default to public. Why? So you would contribute to the greater community without having to think about it. If you truly wanted to keep a secret, it would be an option.

BUT, this service is very far off from what Facebook let's you upload and share. Though, the point is the same, they're being selfish at individual user's expense.