Three quibbles, Bill:
First, pedophilia isn't always a sexual attraction to children's bodies. Sometimes it's a sexual attraction to a power dynamic or situation. The power differential between adults and children physically, mentally, and emotionally is huge, and it's no secret that domination and manipulation can be turn-ons for some people.
Second, a 13-year-old is about as "primed and ready" to have sex as he or she is "primed and ready" to drive an off-road vehicle or mini-bike. Yes, physically speaking, young teens are basically equipped, and they may be keenly interested and eager; even so, they lack the judgment to assess all the risks properly, and are incapable of understanding all the possible consequences and surrounding circumstances.*
Of course this is true whether it's teens messing around with other teens or adults messing around with teens, but the adult-teen power differential is, as I mentioned, huge, and the potential for exploitation is obvious.
I agree that a prepubescent child is different from an adolescent child physically, mentally, and emotionally; but even an adolescent is still physically, mentally, and emotionally immature.
Third,
this xkcd comic on free speech seems apropos. Don't miss the mouseover punchline--run your cursor over the picture to see the alternative (or in this case, supplementary) text.
* (When I was a kid in a rural town in the Mojave Desert, the kid across the street drove his all-terrain vehicle for years without incident, before he died driving it halfway through a chain-link fence on his parents' property. He could operate it just fine, physically speaking. It was his judgment and risk-assessment that were still underdeveloped.)