I agree that the devs fully deserve the support, and a higher price, but I get the impression that the situation is that Hollow Knight was basically infinite money hax for the devs, so they were comfortably in a position to work on Skong for years, and release it at a bargain price to be nice. Even given its bargain price it's probably still gonna end up being another round of infinite money hax for them.
It's like when Untitled Goose Game was a huge viral success, the devs were like (paraphrased) oh sweet now we can just work on whatever the fuck we feel like without having to worry about finances.