It's actually the contrary, Aliens are more like "forethought" (pretty sure it's not the right word but oh well
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).
This game was set out as a very creative alien gay porn game. So if you are still early in the game, there are still tons of amazing Alien contents.
But it degraded very quickly into this "Human / Human-reskin in space" fest you see now.
No idea where it went wrong.
But from the dev perspective, Alien contents are much more difficult to create, if they just want easy porn money.
Yeah I also Don't think they will add Goblin crewmate, as they drew the goblins so ugly.
About the gender stuff, I hvn't (and probably won't) try it myself, but I heard the dev put extra effort into addressing Female MC so all Female Scenes are correctly described.
Are they stopping doing it? Or you messed up your savefile somehow? Maybe it's a problem with Futa / Trans MC? Never heard of anyone talk about those.