Unless Void wants to clarify otherwise, futa/female-only races could always reproduce by other asexual means like parthenogenesis (and before you ask how giving birth through a penis works, look up hyenas). So sexual reproduction needn't be necessary to continue the species. Given the overall interest futas seem to have in men on a sexual level, it might simply be the fact that they find being dominate over men more sexually gratifying. Void said that you mostly interact with those who are interested in such a thing (which fair, it's a fetish porn game). But for the sake of argument if we take it at face value, it seems to be an overall trait that futas in this universe are more drawn to fucking males. Maybe females are incompatible with futa cum and can't conceive from it or something.From the Alien Sheets I read, some alien races only have females and futas as genders. Wouldn't there be a reproduction issue if the futas are mostly attracted to human boys rather than mating with females lol
Of course I'm entirely overthinking all this shit, but as someone with deeply-seated interest in sci-fi and biology I can't help but speculate. A good chunk of futa games tend to just handwave how they even exist in the world at all (or they are "true" futa with both reproductive organs to still reproduce conventionally) so I doubt it's necessary to have an explanation as to how such a thing works in SP since, again, porn game. But some extra lore of the ins and outs of what makes futas tick would be interesting to see.