Hey there champ, let me elucidate you on some points. While the game is being crowdfunded by a number of generous people who don't use this website, and who I'm grateful for because it means I can do this instead of getting a real job, this is first and foremost a personal project. It's not designed by committee or catering to popular demand, and I rarely do supporter polls. I set out from the beginning to make a game that I wanted to play but couldn't find anywhere else, and with few exceptions everything I add to it serves that goal. I did start with feral partners, and then later added anthro partners (though the first build with anthro partner support was less than 2 years ago so not sure where you're getting your numbers), and over the last year or so have been focusing on in-game animation tooling to support user-made content and streamline the animation process for me as well. This is in service to longer-term goals for the game, which extend beyond "there is a feral and you do sex to it".
Let's think about how a game like this might grow, aside from becoming something other than a furry sex sandbox. Starting with feral/anthro interactions as it did, where do you go from there? Adding more sex positions sure, but there are only so many of those. If you want the world to be any bigger than two characters, will it be populated entirely by ferals aside from the player? This opens up some more possibilities for three-way and other multi-partner interactions, which incidentally are the focus of this next v1.8.4 build. But for more variety in the experience, sooner or later it will need to support either anthro partners or some other body shape, and given that anthro characters already exist (the player) that is the place to start. Also, supporting anthro partners (and later feral players) then opens the door to actual multiplayer support, which is another long-term goal for the project.
As to why people support the game, I imagine some are only interested in the feral content as you're assuming. But most every build adds to or refines the game in ways that affect anthro and feral partners, so it's not as if people are being left out or ignored just because new content is added that doesn't perfectly suit their interests. I don't generally know why most people choose to subscribe or unsubscribe. I just keep doing what I do, and there are enough sufficiently interested people to keep that going, so it suits me fine.
tldr this is not "feral game", this is "my game, which has ferals". Hope this helps.