That is not the point of Facebook. The point of FB is to capture connections. To capture who you know, and who interacts with you.
For now, this info may be of no value to anyone. But if you, or anyone on your FB lists BECOMES interesting to anyone, whether through being involved in some event, or having some position of influence, then knowing everything about that person's connections, and being able to sift through it all within seconds of that entity deciding to take an interest -- that info becomes very valuable.
You never know what the future may hold, and information, once on the Internet, can never be called back. You may not think you will ever come to the hostile attention of anybody. Can you be so certain that none of your kids, cousins, nieces, nephews, etc will ever be subject to hostile attention.
To tell you the truth, I think of some of the things I used to say on FB before it got too hostile and wonder if I’m not already in the Obama’s deplorables database.