The thing is, localised advertising is the sweet spot that i've identified in advertising value. If you forget all other data, this is one piece of information that can provide value to both consumer and small businesses.
Facebook, if you know any small business that have a specific region of operation (e.g. one city) derive significant benefit and growth from Facebook's targeted advertising that they just were not seeing before.
Of course, if anyone logs in and fetches their data from facebook as a download and go through it, it is really rather unbelievable how much data there is beyond geographical data. Some of it pretty scary.
What intrigues me further, after i tried to do the same with google, i don't believe google are nearly as open to how much data they hold on a person. There doesn't seem to be any takeaway service that indicates the same depth of information. But of course we know for a fact they do hold some of it.
Anyway, the long and short of it is advertising is all we have to support enormous social networks and I feel some level of personalised data provides mutual benefit. It should of course all be opt in with no exceptions.
I'm actually conceptualising a service/product around this concept right now.