I don't see how it makes much difference. Removing the link from the site means that nobody will discover the photo. People who discovered the photo and saved the link could equally well have saved the file, and in fact I think saving the file is more common.
I doubt that. If the image is being removed, say because it contains an embarrassing picture that was accidentally posted, you can bet someone copied the link and shared it or posted it somewhere. Also, image lookup services like tineye could also grab a hold of them unless they are gone for good.
Don't get me wrong, I still believe that posting ANY picture on Facebook you don't want the whole world to see is just plain stupid.
Let's remember that it's not only the people in embarrassing pictures who upload them. Sometimes rude friends or colleagues take pictures of us without even telling us, and upload them.
Even if you don't save it explicitly, I find my browser cache is full of facebook photos when I go to clear it, so can retrieve it through there after the fact as well.
There are lots of non-technical users who don't know about saving files (seriously!). Removing the original link would cut off some people from access to the file. It's like computer security. You can never be "100% secure", instead you start taking steps that each will reduce your exposure.
Not only that, there are potentially legal differences between publishing a link to an embarassing photo and actually sending the photo itself. After all, it's common on this site to draw the distinction between linking to content and the content itself.
With the photo in their possession, they may crawl it sometime in the future and extract (via computer vision, facial recognition tech, whatever) further information about the person, their friends in the photo, etc. if they hadn't done it already. They may mine the metadata in the image itself for camera GPS position, etc.
There is still very much value in these photos, and a great chunk of it can be unnervingly personal.
Because no one ever shares links online ... email, twitter, delic.io.us, pinboard and pretty much every other method of communicating excepted, of course.
