The Patreon guy said in the final part that people didn't really respond well to the new art style, but I'm betting it was more the ridiculous story development. This series started as a silly, slice of life story about a succubus trying to get a stubborn guy, and falling for him in the process. Those are fine, I happen to love Shachiku Succubus no Hanashi, it is both sexy and absolutely adorable. But then this story turns into a dark, battle story, where they are fighting against the combined forces of Hell who decided to say "Fuck the World!!". Again, this could have actually been ok, if it had been done slowly and properly, developing the new storyline and allowing it to grow it if the old one. This just said "Hey, the is a cute little story we're doing here, and the readers seem to enjoy it. But instead of continuing that, were going to take everything we've built up, shove it into the dirtiest trash can we can find, get a few homeless guys to shit on it, and then set it on fire! The readers will love that!!!"