Not only that, but in order to make money from advertising, they link all this wonderful data (your data) with advertiser interests. Much of this linking is done under the radar, via rules you are not allowed to see.
It's very important to distinguish the benefits of shared data with ownership and control of the data, and the rules by which it is mined and accessed.
BTW, a lot of Facebook data is "self-expression" and if given the choice in real-time, many people would elect for NOT for their contribution to go into the tech-giants mainstream database. Going into "settings" and messing around with broader privacy options for content types and particular people is an absolute joke in terms of UX and human experience in relation to expressing personal views or communicating with friends.
"Privacy settings" does not come naturally in communication. Facebook knows this, and knows people will not bother or become lazy with privacy.
Bottom line is, Facebook is an inappropriate platform for the collected data that is your life.
The big problem in the future will be the fact that as the line between "real" and "online" life diminishes, the party which holds the data will become an authority akin to governments we have today. When or why should we trust an authority? How can we be sure that the authority is trustworthy? Politics is hard enough and we all know that we can't trust politicians, how on earth are we going to trust a party with commercial interests to somehow manage our social lifes?
You seem very optimistic about things like Facebook collecting data and interlinking people's social life via their platform by using the collected data. I for one find this very scary, to such extent that I'll rather cripple my social life and not use Facebook than trust an commercial authority over the data collected about me which I have no control over.
I provide the data. I see the data. I own the data. I control the data. What is so hard about it? Honestly.
Also, not using facebook is difficult to imagine for me. It's pretty baked in to my life.
The thing is, Facebook could be better by allowing members to invite outside data to flow into their feeds from chosen sources, and providing more freedom with data-exchange in general. Enforced segregation is costly.