Public display? Personal life? Surely, if you do not wish your personal life to be published on Facebook, you don't need to post statuses about it. You can also monitor what kinds of information is displayed and whom can see it.
The reason Facebook is popular is because it's an ease. It allows easy communication between a group of friends, one to one and from Facebook you can show off occasions, events, places and links. It's the best thing the internet has to offer. I believe it's also popular because of it's growth, with some many people on Facebook, anyone who gets the internet gets Facebook - it's inevitable; without it, we feel left out.