Ermm, what's the big fucking deal *****?
So two consenting individuals want to share naked photos of eachother? So what? Let them, it's not like any actual harm can come of it. I don't even think it's that big a deal if they aren't of legal age to do so (to an extent).
The only thing that matters is if you trust the person you are sending it to. And perhaps being a little discreet about it too. But even then, worst case scenario some people might see you naked... And? Like they've never seen or will see a naked body in their lives! And if you've got one worth looking at then good for you, having a great body is worth way more positive points than having points subtracted because someone else saw it.
You gonna tell Michelangelo that painting all those naked people is a sin against the laws of decency? No I didn't think so. And if institutions like the church want to condem the practise, perhaps they should lead the way by you know, taking down all the pictures of naked men, women and children they keep lying around... Fucking hypocrites!