I think someone asked this question before but I can't remember fully what was said, I don't think it was answered too precisely.

So what is the reason? I came up with my own possible reasons instead of just simply asking the question because... because... actually I have no idea why I did, because I'm kind of sad I suppose. And I want to have a guess at the reason.

* The girls find it invasive or don't want someone they know seeing them naked. I think something like this was offered as the reason before, but in fairness... they're an escort! Not exactly a job for a girl who is very shy about her body and likes to remain 'chaste'.
* They might make men too aroused and this makes them less likely to casually look over the girls, especially when not alone.... they can't masturbate and it could make them uncomfortable.
* There might be a lot of legalities involved, maybe it would be legally termed 'pornography', and E-I doesn't want to have all that overhang to deal with.
* Maybe it is felt that if some girls are allowed do it, they all will.

Thinking over it, I'm tending to think it's the third reason. Otherwise, why wouldn't there be other websites out there doing it to get attention...