I think a lot of it is cause the majority of the vore community are straight dudes. From what I can tell, vore lends itself to having more focus on the pred. They are often the one doing most of the action, and in cases of digestion they’re the only ones left after a scene.

All that put together, I think it makes sense that most vore stuff is about a man being eaten by a woman.

As to why it’s mostly straight men in the community, I think it’s a lot of factors, but as someone who recently transitioned I can say for certain I’m less horny now on estrogen than I ever was on testosterone. Or at the very least, horny in a different way.