When it comes to something as sensitive as user privacy, no mistakes should be made.
You can't just excuse a criminal for stealing thousands of diamonds because he may have given a few to a charity. That's a poor example but I think you get my point.
I think the issue is that Facebook makes the same mistake repeatedly, indicating that it's not even close to a mistake. It does something its users don't like (erodes privacy, design changes, automated sharing, etc), claims it's good for them, then partially backs off.
