It seems that some "application" that I had used on Facebook required SSL to be temporarily disabled. I don't remember an application saying that SSL had to be disabled, and I'd be the sort of person to read these things. I'd worry that this would be a problem for less techy users.
SSL should be an opt-out feature for anything that harbors personal information. I can only assume that this isn't the case due to the extra server overhead that FB would have to deal with ?
Another source of confusion is that nether the iPhone or Android native facebook applications respect the HTTPS setting, so to use HTTPS for facebook access on a phone make sure you use it via the web browser not the native app. IIRC this was one of the bugs: accessing facebook via one of those apps would reset the switch for next time you accessed the site by other means, whereas now it doesn't.