Hey littlecat, I think you raise some really good points. I do use facebook but it's mostly a directory of contacts, only a small handful are true friends and a couple of my closest friends aren't even on there. It's all about expectations imo.
It is very useful for making social/sports arrangements with groups of people, and also keeps those who are dear but far flung away from us in touch. I got to see my beautiful new baby cousin born the other side of the world care of facebook. So there is plenty usefulness and good to be had.
It's a case of sorting the wheat from the chaff imo.
I don't friend people I haven't met but don't look down on those who do - after all all of my friends on pc are folk I've never met.