As a matter of prudence, I am inclined to agree with the arguments of the questioner--if one does not want others to photograph one's exposed breasts (or other body parts), one should keep them covered in public.
On the other hand, I don't think that the issue is quite as simple as this. The man who was arrested admitted that he used the photos for his own sexual gratification. But what if he was posting them on a website--perhaps for profit? I think there are somewhat thorny issues here, and do think that the most important ones have to do with legal protections of personal privacy, and where the lines get drawn on this issue. Does appearing in public mean that anyone can photograph me for any purpose whatsoever? That does seem a bit much to me! Here is another example--what do you think of the idea of a pedophile photographing children swimming or running around on a beach in the nude (as one can see in lots of places in the world)? No problem here? I guess I would caution the questioner that the obviously prudent reply that he or she provides tends to mask some important issues about whether our privacy should still be protected from various forms of intrusion even when we are in public--and I guess my own intuitions on this are somewhat mixed. Although I agree they should not be as aggressively protected as when we are in private, I don't think it becomes "open season" when we are in public, either, no matter what we are or are not wearing.