Calling "suggesting a change and asking users up front to confirm or correct it" unethical strikes me as sensationalistic. The fact that a large percentage of users didn't just click through the thing (i.e. it wasn't some stealth decision forced on users) doesn't make it less ethical - if anything, it makes it more so.
I don't know if unethical is the right word. Maybe "shady" would be better?
If Facebook wanted to stay on the safe side of things, they'd have kept the default as the more private setting and then show some kind of prompt saying "Hey, this is a new Everyone setting. This is what it does. Would you like to try it?"
