There are loads of angles to this subject.
Unfortunately I have a lot of experience and knowledge in this area, through no fault of my own. 
There are plenty of case studies, individual stories and theories from experts, that have linked the increase into child porn as a direct influence with teen porn.
Surely if some guy is particularly interested in 'barely legal' 'young girls' then they are jacking off to the idea that she looks underage. How is there nothing wrong with that?
This article sums it up for me.
here
Did anyone every see the stats from the founder of OK Cupid on what age most men prefer their partner to be? Women's tended to match their own age give or take a few years. I think the men's answer's only differed by 4 years. They all chose either 20, 21, 22, 23, or 24. That was men from 18 to 60!!!!
It's more of an eye opener to read the comments at the bottom of that article. It's full of 18 and 19 year olds telling their individual stories of 'creepy' and 'pervy' men in their 30's and above hitting on them.
I wonder if these sad losers realised how teenagers and young women really feel about them? I suspect, they would just revert to calling them 'slags' and 'sluts' and how they're not 'all that' if they did.
Evidence of this here
This is another good article from a man, explaining it quite well.
here
Like i said, i've read a lot, watched a lot, talked a lot, as this is personal to my life.
I'm still here for now, but unfortunately respect doesn't grow back.
Go figure......