It's probably due to the lack of interest in our fetish. Erotic hypnosis is already very small, and when you tack on gay males and images only, you only find a small selection of people. And even smaller is the group of people in our festish who have art skills and enjoy drawing porn. So people run out of content and those who can't draw try to make more.
I did come across a couple manga scanlations with hypno in them, but they're mostly untranslated.
Maybe we should get some translators and art commissions. //shrugs-