I think the real problem is that Mark Zuckerberg has the opposite belief, and thinks everything should be shared with everybody.
What I don't get is, why doesn't somebody just build an alternative to facebook which treats your data as private and not public. Then you could have the people still on facebook install an app to allow the secure-book people (or whatever) interact with their data so everybody can be friends across platforms. And maybe another app for vice-versa usage. bada bing bada boom.
That's a great idea, but the Facebook app will always be the weak point, because everything you share (to specific users) through it will still be open for Facebook to use however it sees fit.
I like the non-flat approach to social networking. Most of my facebook friends are there because we went to high school together. It would be nice to be able to group them apart from my 10 or so current friends, so I could not snub my acquaintances but keep in touch with those who sould be kept in touch with.