I used to belong to the Guild of Erotic Art (now disbanded) and there was certainly a high percentage of male members (not in that sense!) who specialised in painting, sculpting, but mostly photographing the nude female form.
Yes, some were highly skilled photographers. There were very few women, and the women that were members, were often models. A case of supply and demand you could say. So why the difference. It is possible that when men paint women, they are painting what they desire to have…and society sees that as acceptable. When women paint erotic works, they can end up being judged on a number of levels. Their sexuality and sex life can be questioned. I am not a feminist, but I do find this yet another example of inequality of the mind. Speaking for myself, I paint feelings and experiences expressed through the genre of erotic art. I paint women I would like to be like, women who I can pretend to be. They are characters in a story and I am the author.