It's been discussed before, but people that play these games tend to fall into two groups. There are those that enjoy it for the porn and game value taken as a whole. Then there are those that "self-insert" into the main character. The main character becomes a placeholder for them in what is going on. That second group prefers an antagonist that is their same gender and if they are somewhat generic or even don't have a face (as in some hentai games), so much the better. Things like being able to rename the MC and being given choices that change the game tend to be important to them.
Both views are valid and both are pretty big groups, although having a male protagonist will attract the wider audience because it can appeal to both. Personally, I'm the type to see myself as the character, whether it be in a book, movie, game, or whatever. In fact, imagining myself in the action is part of the fun. But there certainly should be female protagonists in a game if the Dev wants one, or just for those people that prefer it or don't care one way or another. They just need to be aware that the "female protagonist" tag is one of those that makes some people avoid the game just because it's not for them.