I'm only an occasional user and have about thirty people I know on it, I pop in an have a nosy then close it down.
It doesn't bother me if I see someone I know killing their boredom playing pointless games, or if they're feeling a bit lonely and posting some random shit on their status, I just think well I'm glad I've found MN to get any whinging I have to a wider audience 
I know it can cause problems, SIL did three status updates about her mum being in hospital but didn't think to tell DH (who wasn't happy about her thinking fb strangers should know before he did), but unless you're going to cut yourself off completely from the rest of the human race, any communication with anyone however you do it has the potential to cause shit.
It does seem to be looked down on by a lot of MN posters, is it because you're all so old and not in with the kids? 
A bit like when mobile phones first took off (and computers/videos etc) and the olds predicted the end of the world as we know it, but it's turned out not to change for the better or worse, it's just different.
People are still the same, nice to each other one day shitty the next, nothing to do with facebook or phones, but just people being people.