Thats a good point as far as your visual identity being exposed to other fb users. However, with where facial recognition is at now, they're sure to be able to match that and your identity on their business side with your (IRL) friends location data, cross site tracking and other data to effectively have a db of images of ‘you’. Whether or not they have a business use for it is another matter but not a stretch to see it as a part of the data harvesting and broking landscape, though I’m not sure of the value of images of you to them : perhaps demographic data for adsales. All speculation on my part, and I’m not sure where this would sit with regulation in various places. Just interesting to think about.