I'm pretty sure that people have been taking photos of themselves for far longer than we've had a catchy buzzword for it.
Not really sure as I'm seeing a downside to it. Almost everyone has a profile picture, and if the laydeez want to post pictures of themselves I'm not about to complain. (-: Frankly it's preferable to the bulk of the Facebook output in my feed at the moment, which seems to largely consist of photos of my new dogs being "cute", photos of my new children being "cute," clichéd saccharin-sweet motivational pictures, and photos with captions describing how (football team du jour) are onanists. I think I need another round of de-friending people who I spoke to once in primary school.
I suppose it's that 'moderation' thing again, isn't it. Taking a couple of pics to show off your new t-shirt / haircut is one thing, plastering FB with dozens of near-identical pictures of yourself is perhaps a little too "me me me" for comfort. But hey, it's not my business.