Much as I love complaining about Facebook, the fact that they accurately derived the pages to be linked to means they already have this information. In fact I'm not even sure why they bother to ask.
Also FB has had backlash before over making things public so they are trying to nip that in the bud beforehand by allowing the vocal minority who understands/pays attention to this stuff to opt-out while the masses just click the "Accept All" button.