Basically, the point here, according to a judge, is that it is the place that it is done, not the part of the body shown. As opposed to a place where someone would expect to have 'reasonable privacy' (i.e. home, changing rooms, etc.), a person's picture can be snapped in a public place without their knowing it. Face it, this happens every day. While they agree that the actions here may be considered offensive, it is not illegal, because the subject is in full public.
It raises the question of personal privacy, sure. Does this mean that a woman wearing a skirt has no recourse to perverts snapping pix of her nethers? Well, keep in mind that if the person in question uses those pix for anything, whether profit, promotion, or business, then you have recourse, just like any other picture of you, becuase you didn't consent to the release or use of those pix. If they don't...be honest, what you don't know isn't hurting you. It boils down to how Puritanical one chooses to be about their skin and body (which I ranted about not too long ago). That's a personal choice, and not one I plan to change your mind about, but I do have my own thoughts on that.
I'm not trying to say I support perversion...no, I take that back. I totally support perversion. Frankly, I'm glad to see the Justice System actually thinking something through and not decideding something based on somebody's personal morality.