And how is medical information any different from financial information? Financial information can be used to do exactly everything you said about leaked medical records, yet no one worries if their bank/identity has been compromised.
It may seem trivial, but most people would be less shy about most of their transactions going out in the world than naked pictures of them in compromising situations.
If I didn't know it, why would I care?
If I did know it, then I would care a great deal, as HIV is still very much a stigmatized infection.