No. It's not. It's just not something people like to risk doing.
The problem for me with the games here is that most female protagonist games are... shit from my perspective. The amount of games that are based on "you play as X, go out and get raped in RPGM" is staggering. I don't like playing as the one being trampled. I'm the player. What happens in the game should depend on my choice. It's the same difference between good BDSM and rape - one is a choice, the other is forced upon you. And while I have no problem with ANY type of content in principle and if there is the audience for such a product - good on the devs making it... it's not my product. I don't play such games even outside of the adult scene.
I'm also kind of not interested in the tropes used when writing with a female protagonist. The settings, the characters, the plot, the drama... meh. I do not care about schoolgirl problem. Now, if you let me play as a succubus trapped in a human body and my goal is to corrupt a bunch of people. Ok, now we are talking. Or maybe twist the usual stuff - the protagonist gets abducted and used as a sex-slave, but has the options to ether loose her individuality, slowly turning in to a brainless drone from all the abuse or embracing her new life and making the most of it or even better slowly using the week points of the men around her to turn the tables on them. One can write a pretty crazy corruption game with such a premise. But no, 9 out of 10 female protagonist games I've tried just have no choice in them.
Part of my preferences is that I am a dom, I like dominating people, I love the corruption concept (tho outside some forms of mind control/blackmail/magic plot there are very few games it's NOT done horribly bad). I see no reason one can not just gender-swap the protagonist in most such games. Honestly considering the abundance of incest games, playing as the little sister, who actually want's to A) bang her hot-brother(s) and dad, B) bang her hot sister(s) and mother and C) watch them all bang each-other would be a refreshing concept. Basically, why are there no options to go in to the perverted aunt role? You know, the character who actually gets off on corrupting their family.
The main arguments I've seen are both dumb - nobody wants to play the slut and women don't work that way. The first one is just wrong, IMO, tho it has some merit (just look at how game-threads turn when any option of sharing (or even worse - NTR) is introduced). The second one is just wrong and kind of sexist - women have the same capacity as men to be perverted, evil, no redeeming qualities people as men do. And yes, women have a libido, women can be creeps and so on. Like, go befriend a woman. As a real friend, not as a potential girlfriend and get to the point of sex talk with friends. We are not that different.
And we don't really know how much of an audience there is for such products. And like it or not, this is what in the end drives most game development. Devs have to pay the bills in the end.
I'm pretty certain the "most writers are male" is not the reason we don't have such games, btw.
frap nails it on the head - they are characters. If you write them as just that - characters, slapping the relevant genitals and sexual orientation is almost an afterthought. The whole problem probably comes from people thinking there is anything special about writing women, minorities and so on. Nah, there isn't one. Don't listen to a handful of tumblur idiots, who pretend there is anything. People have written whole movies with gender-neutral scrips ad they worked spectacularly. But every time people decide there IS something special... well, you get the Ghosbusters remake.
The problem is, since time immemorial there will be a woman, who would not like your female character and go on to complain about her. Here is a hint - most such complainers have no idea what they are talking about. Does your character have goals of their own and do they act upon them? Cool, their gender/sex/race is irrelevant. A good rule of thumb.
PS: I also bet a lot of devs actually have much better and fuller sexual and social life than the people proclaiming porn game devs are some basement neckbeard incels.
