Wow, this got ugly quickly.
Let's take a step back: On one hand, consumers have every right to want something different out of a game than what is initially provided. Just wanting something different isn't an insult to the developer; in most cases, it shows that one is invested enough in the game already. Toxic gamer culture is just a vocal minority. On the other, so does the developer have every right to make the game how they want it to be.
Mass-produced AAA games are often held to a different standard on appealing to different audiences since they are mass-produced and influential in culture. These days, most games that don't allow customization are those in which the player character is an entire character of their own, such as the Zelda games. Now that the technology is advanced enough for it, customization adds to one of the major reasons people enjoy games; feeling like one is in the game, in the story, so to speak. Considering the feel of the game, I, personally, find it a reasonable idea to add in custom gender and sex settings. Not knowing much about the developer or development process of this game, I am of course poorly informed to come to any actual conclusions, but note that most players are casual, coming to this game through the Game Jam page or tag searches. I believe that if one sets out to make a living off of media, one must be willing to welcome any and all paying customers.
As mentioned above, it's entirely possible that having a male protagonist is intended to be inherent of the game (though this is rather self-conflicting since the game gives you quite a bit of customization options), but even if that were true, having an option to play as a female protagonist is still a valid option. I have not the monetary means to support this game, so my voice likely means little, but I hope it at least means something that I've played and enjoyed it. Like ShioriS said, there are almost certainly other people who would appreciate more character customization and may even be driven to support/support further as a result.