The stereotypical use of Facebook, Twitter, Google Buzz and similar services is to share things with everyone. Either everyone in your friends list, or possibly, everyone in the world.
The group of people clamoring for better “privacy” are asking to change this to a service in which we share things with exactly those people we are interested in sharing them with.
I believe most people would continue to share with everyone by default. Indeed, Facebook already allows sharing with specific groups, but do people really use this feature much? The reason is, it’s easy to publish to “everyone” and hope someone might be interested. It’s much harder to publish to “specific people” and wonder if those people would really be interested in what you have found or what you have to say.
From the other side, it’s much easier to ignore something that a friend has shared with “everyone.” We simply assume that friend had other people on their list that would be more interested. On the other hand, if someone explicitly shares something with me, I immediately wonder why. Why did they think I would find it interesting or entertaining? Further, if I don’t find it interesting or entertaining, it is harder to ignore, because my friend has made a special effort to share it with me, I should express interest.
Facebook doesn’t facilitate easier sharing of information. We had that already, via e-mail, instant messaging, chat rooms, blogs, websites, and countless other services. Facebook allows us to easily ignore information. That is it’s charm; to imagine that we are being heard, without having to listen to anyone else.