The problem with Facebook is not that it is public or lacking in privacy controls (it is silly to think that any real privacy exists on the Internet). The problem with Facebook is that it is greedy. There is no clear path to profits for the individual user. No equivalent of Google' Adsense, nothing like YouTube's monitization feature.

Google+, which I am a member, but have little use for, also has no profit sharing features -- and the same goes with LinkedIn (useless to me).

Hopefully Google will extend its Adsense program to Google+ -- it would be a distinct competitive advantage.