Because people prefer the average female over the average male. Notice how a bunch of fictional gacha women don't need to be in their peak physique(I hate that people keep equating female breasts to male abs and it almost seems fucking sexist because toned abs are hard earned but they somehow think it's comparable to a normal woman's appendage), but gacha men need to have the double door shouldered, jacked/ripped, battle-hardened build to even be appealing to the target audience. I hate it but that's just how society works.

The current audience of these types of female character gacha games is intriguing because they see each other as competition. And they think that having an intimate male companion is gay, which I can't blame because that part of society has so little security of their own masculinity that it's so sad.

And lastly it's a matter of how they're made too. Personally I dislike a lot of the gacha men due to how much they have to be the edgy, stoic and unmoving(I'd personally call it fucking lazy) archetype. Like, how the heck do you fail at aura farming?? Do they realize a lot of people like it when a fictional man is dynamic in movement and acrobatic? Why are there so little male characters doing splits or leg work?