Humanoid enemies are quite frankly very uninspired in my opinion. I think there IS a place for them, but it needs to be done tastefully. Erotic games have to find the balance; tentacles, slimes, eldritch creatures are sexualized because we don't understand them. The concept of us ( or whatever we deem attractive ) being convinced of a crazed sexual nature, one of obedience and/or serving is attractive because it's a level of pleasure and compliance we don't understand. Watching our protagonist do these outlandish things for/to these beings, against their better judgement, and more so not attempting to fight back- tells a very troubled and uncertain consent to this otherworldly pleasure. Ultimately, giving into this pleasure and forsaking previous morals.
We know the feeling of desire and lust, in fact, it's one of the most feared sins for the reason being that it IS you. It's what drives you, the push for pleasure, so overpowering that even the Bible tells you to RUN from it than to fight it. When it's offered to you, suddenly, before you can even react, and when this horrific thing undresses you and makes you feel absolutely delightful, there's a bit of you that loses. If this unknown entity is offering you a lifetime of that, and wants to care for you and make you a seedbed ( or a seed producer ), you hesitate. What if you could just walk away from society and just be here forever with this "thing" that ensures a pleasurable remainder of your life, what if it could melt away all the expectations and needs of a job or shelter. It'll keep you safe and warm, forever.
Versus, there's this weirdo who's been stalking you and wants to have sex with you. He's like, 39. He left his day job and family to try to capture you and rape you. Eh, I mean sounds like a fun time but the police will probably find out. His fetishes are "BDSM"... oooohhh, how unique... So you're gonna slap me with that whip made in China? Very cool... I know I'm chained up in your basement or whatever, but I can smell your Wendy's from down here. Woow, he's using a condom? I mean- you went this far why look for protection now? Ahh... Missionary, how devious of you, Greg... For Goblins it's almost the same thing. You're entire life is to stuff your semen in me, and now I live in some cave forever with these gremlins who want to do the same ol' vaginal and anal dance! Such a sad way to go out!
You know? It's boring! Not trying to shame you guys for liking it, but come on! I know you have better fantasies!