Just food for thought here, as any adult taking such pictures of children is clearly a piece of shit who needs to be removed from society...
But the thing about children is that they grow up, into adults who can consent to the continued existence of pictures of themselves. And what of minors who take such pictures of themselves, who then retain those pictures as adults?
I can see the reasoning behind blanket bans, as it is difficult to differentiate between a picture that fits the above situation, and a picture taken of someone as a child who does not wish it to continue existing, but there are probably better ways to handle the situation, such as releasing the images to a database if and only if the grown adult in the pictures consents to it, and then requiring users who want to view them to register. Not registered, but have the pictures? Crime. Have pictures that aren't in the database? Crime.
Such registration would serve many purposes: allowing pedophiles an outlet that doesn't require them to create new victims, and providing a mechanism to track pedophiles and which would provide a social reason to report those who skirt the system are just a couple off the top of my head.
And what do we do when technology advances to the point where we can decide the shapes of our bodies? What will we do when someone decides to be child-sized and child-shaped, and to start making weird porn? Or when someone decides to depict that in highly realistic art, today? If we don't have these discussions now, before it happens, we won't be ready as a society when it suddenly IS happening, and we'll probably make some tragic mistakes.
There are clearly problems with the 'children can't consent' argument, and they are only going to get worse as time goes on. I would far rather we have a social mechanism that doesn't drive people who AREN'T molesting or taking pictures of children to have to associate with and shelter those who DO abuse children because that's the only way they can satisfy the needs that a fucked up existence forced on them.