For anyone with teens it could become far more important in the future, if they post inappropriate content.
On a R4 programme about privacy, someone from a widely used search engine service said that while his firm has no really easy way to find a photo of a particular person, it is superb at not just allowing searches, but of archiving material (hint Google is involved with www.archive.org which runs the "Wayback Machine", so you can view websites from 2005,4,3,2,1 and earlier, in many cases)
His advice for his teens was to put as little as possible online about themselves, if there was the slightest chance it could portray them directly or indirectly in a bad light (not just the drunken party while underage, but being in a bunch of friends where several take drugs / steal cars / etc).
It's becoming routine for universities and employers to search for background info and that can prevent getting even an interview.
Now, quite agree a teacher in her sexy lingerie (where, where? ) is just being daft, but putting any 'dubious' pix online means that those who are 'friends' today can take copies, and can post them elsewhere anonymously (or masquerading), thus making public that which one (wrongly) thought of as being 'restricted to friends'. Then it may be archived and be visible/findable for years, perhaps blighting a career.
Simple example, but allowing any 'access' means any 'privacy' should be forgotten (sorry if that sounds too negative).
Remember the e-mail that went from gf to bf (about their night in bed), was then shared with his friends, and then went on to thousands.
I think a half dozen or more lost their jobs over that (daft to ever use a 'work' mail address for anything in your private life, and no excuse for doing any of it on work network, it's bound to be covered by company policies and archiving of all "correspondence" may be automated to ensure a "paper trail" for contract / compliance reasons.
It's an area I am concerned about for my nephews and niece, given them being under 30 and with a number of friends from work/study, whose friend-of-a-friend ... links must wrap around the UK/ Europe/ World and among those people could be all sorts who snort coke, commit fraud, etc. They're not all in the UK, and when studying, had friends from as far away as Japan.