So what is it?

In Sydney, Australia there has been a big controversy recently about an exhibition of photos by a renowned artist photographer, Bill Henson. Several of the pictures showed a naked fourteen year old girl. Members of an anti-paedophile group complained, and the police closed down the exhibition. You can already imagine the huge argument that followed, with some saying that it was art and should not be censored, others saying that the pictures had the effect of sexualising children. In the end, no charges were laid against the photographer. Members of the child protection lobby still insisted that the pictures were objectionable, art enthusiasts insisted that they were art.
I won't claim that I can say whether a thing is art or not. One question does occur to me, though: if art is concerned with the human form, why are so many images of the young female version of it? The human shape includes both sexes and all age groups. I'm not being critical about young girls here, just saying: why only young girls, instead of older women and male people as well. Come to that, why has a person got to be undressed before they can make an interesting picture? Being seen naked can feel like an invasion of privacy. And some brilliant pictures show people wearing clothes.
If anyone has any thoughts on this, I'm ready to hear them. But it's been this way for as long as I can recall. Artists with an interest in human nudes seem rather restricted to young women, not the whole range of possibilities. And does the naked body show a person in an intimate, potentially sexualised way?