This is stupid reasoning, on multiple fronts.
As for "in development for 20+ years", just beacuse he made the first version over 20 years ago, does not mean it's been actually developed during that entire time. Although they are clearly built upon eachother, they still have quite big differences, Feel the Flesh being very barebone and simple, with Rebirth being a revamp of the game, adding features, more outfits, backrounds, possitions, and increasing the graphics quality on everything; He finished both of those games, they were not "in development" nonstop during that period of time.
Regarding this game, beacuse he decided to make you able to change colours on almost everything, he had to remake almost every texture, seperate every single sprites linework, shadows and colouring map. If you run the games through a decompiler, you'll see that the previous games just used the single coloured sprites, while TTG have every single sprite split into an absurd amount of different parts.
The Ponytail alone on the hairstyle with a Ponytail uses LITERALLY 125 sprite files.
As for "milking it"; google Kasumi Feel the Flesh, or Kasumi Rebirth, and you'll find both games on an absurd amount of amount of "Free Flash game" sites. I'm willing to bet you almost everyone here played those games pirated on a flash site, rather than gave the creator a cent; even if you googled it on Japanese, you were still be met with several flash sites that was pirating it before you'd find his own actual page.
He have even writen on his Patreon that people who just want the game should stop being members after getting it, and that it might benefit them more in the long run to buy the game on the store instead or just re-joining whenever an update hits.
He've also said that the reason he made the Maid outfit a DLC, was beacuse he knows from the past games that once someone buy the initial game, he stops getting any money, so he plans to make the outfits as a means to keep make some money; the fact that people stay members of his patreon, despite him telling them not too, is not "milking it"; he literally has this on the front page of his Patreon tiers:
"You don't have to remain a patron. This is not a subscription, and I can't promise monthly update of the game. So please support me only for the months you can."
Regarding comparing it to Star Citizen, that has to be one of the stupidest things I've ever heard.
You're comparing a company with 500+ employees working fulltime on a game to a single person who works on a game when he have free time and isn't working (at least last time I checked, he still had a regular job on top of this).