If it's not porn, what is it then? A fashion thread? A "guess whose picture this is" thread? What other purpose could it have but being porn? You don't have to jack off to a photo for it to be porn.
In any case, the american legislators accept the use of semi-naked or insinuating photos for advertisement purposes - bless their greedy corporatist hearths - therefore they made them acceptable for public dissemination also. There's something good about the advertisement industry, amazing as it may seem. But the reason those photos are used is that they are aesthetically pleasing, and the reason we find them aesthetically pleasing is rooted on sexual instincts - don't deny it. Therefore they're porn.
Ah, now it's me supplying ammunition for any self-censoring brigade on this forum to do the "good work" for the moral police. Whatever, I don't care, it's not as if the Internet isn't awash with porn elsewhere. Hell, people are making and uploading their own by the millions!
I am not entirely sure if you are correct in claiming that finding an image aesthetically pleasing is dictated by sexual urges; kids in elementary school are in a non-sexual phase of their lives, but they still find images of people pleasing. I think there is a dichotomy here, both sexual reasons and largely non-sexual ones which make an image of that sort pleasing. It goes down to the common schism between the notion of beauty and the notion of sex-appeal.