Note: For further discussion of this topic, see this previous post (look for the section marked "Additional Point").
If girls were more enthusiastic about spreading around sexy pictures of themselves on the internet, then by all means, I would defer to their judgment on issues of ownership and consent. As it stands, there is a demand for sexy pictures of girls on the internet, and the market will supply one way or another.
Personally, I do not believe there is any serious risk of harm to most people whose image ends up on the internet in a sexual context - except from those busybodies who make a big deal out of what should be a natural occurrence.
But I don't believe in feeding those busybodies' neuroses by agreeing with them that pictures "exploit" people. I don't believe, either, that sex can only be a private, unrecorded act between two [straight, married, adult, yadda, yadda, yadda] people.
As a result, I don't believe most people are harmed significantly by the passing of their pictures around the internet - especially among people who enjoy those pictures. A lot more harm is caused by prudish bullies than by enthusiastic perverts - that's a fact, regardless of what the media does to vilify "nasty sex criminals".
After all, it's not "think of what the perverts will do when they find your picture!" so much as it is "think of what the prudes will do when they find out those pictures exist" we worry about. So why heap all the abuse on the perverts? It's time we put the prudes in their place, and forced them to take responsibility for the messes they thrill to create.
And as long as the female libido is, on average - whether due to biological or social factors - less interested in visual media than the male's, then I see no conflict of interest in men putting forth most of the effort as a proxy in presenting sexy pictures of girls on the internet.
As long as the girls are being properly compensated, there's no problem; I do not believe that explicit violation of privacy and consent is justified, even in this case, however I do believe it is appropriate to take a conservative stance with regards to accusing men of stealing and "exploitation".
After all, the most a girl has to lose is her modesty, and that is a principle she's better off without. It's our responsibility not to judge her prudishly for losing it. Will you stand up and face that responsibility?
In my opinion, if you're willing to shame girls for their sexuality, then you should be barred from enjoying any part of that sexuality. It's only fair.