e-book porn

I've always wondered what makes people invest in (physical) e-books, since the display-technology is still so inferior to normal pocket books.

But there's an area where e-books have a clear advantage over normal books. Porn! The read times are usually short (with me, anyway), you could password-protect access, you can wipe it off (better than paper, at least; and it doesn't have to be waterproof, just splashproof), you can have a few normal books in there just for cover (or afterwards), and most of all - the damn thing stays open without occupying a hand.

Why isn't this happening yet? Or is it?

[How do you turn the pages? Maybe a voice interface. "OH!"]

[Small pictures? I don't think that's a handicap (to wit, the WAP porn sites - how pathetic can you get?); and I think there is a considerable market for both stories and pictures.]