The problem with Female MCs are that male and female sexualities differ quite radical way, in short men want quantity, while women want quality.
A quite generic porn game is where male MC is a student and bangs hot classmates, bangs a hot teacher, bangs one mother who attend at school and bangs also her two daughters. Now imagine that as reverse: female MC bangs her classmates, her teacher, she bangs one father who visits at school and later both of his sons. That plot is awful! And for a reason we call girls like that sluts. A good key opens many locks, while a poor lock opens to any key. The reason why we dislike such a behaviour is because that girl could be your mother, "sorry honey but mom had some fun and got lost with twenty men, one of them is surely your father... I think."
In short if female MC is in the game, the plot needs to be more complex than solving every issue with sex and whoring herself out from every encounter. It is possible to have a good porn game with female MC, yet it requires more designing.