This is terrifying for people who shared things thinking that they were private (especially those suffering harassment). However, as we know, nothing you share on Facebook is private. Your posts are public regardless of what you set them to.
So set your default to public. If you feel as you need to change it for something, don't post at all.
I remember a very long time ago, I inadvertently changed a photo album I never deleted from private to public and it contained photos of an ex. I got a call from my then-current girlfriend with a boatload of questions. I started realizing shortly after how damaging this new (at the time) social media stuff could be. In my case, it was something relatively small, but I can't imagine what kind of stuff other people might have that could expose them on so many fronts. For this and other reasons, I slowly weaned myself off social media and never really looked back. I just use various accounts for logins and a few check-ins here and there.
I didn't have a Facebook account for the longest time, but having moved countries it sadly became necessary. These days I rarely post directly, only update friends and family on their posted statuses.
My distaste is slowly growing into action, there isn't a Facebook competitor right now (tweets, toots, or OpenSocial updates are Twitter, not Facebook). One of these days I will compete with them for no price more than staying connected.
Exactly - I did this a few years ago, and never even blink when I read this stuff. About the only thing I change the privacy setting on is if I'm traveling or similar and want to check in or post pics on the road.
So set your default to public. If you feel as you need to change it for something, don't post at all.