The problem this game has (among MANY other games on this site) is that its essentially a never-ending developing cycle. There will never be a completed project because they always have something new to add, which means there's never a good time to add to the core of it. Its like they're trying to create the porn game that does any and everything but that's just unfeasible and will never happen for any game ever.
Instead they should all focus on the core game first, get the main stuff done or at least the backbone, and then work around that sufficiently without going overboard before continuing. If you're making a game and you can't see a reasonable endpoint in your plan that you want to reach, that is a problem, not a feature and that's not a good mindset.
Even with the best intentions, even with all the features in the world, these games do get old and players lose interest. For example and personally speaking, I have nearly lost any and all desire to continue to play Hero's Harem Guild because it just seems to never really go anywhere. Sure, there is a lot more side content than two years ago, but the main story ultimately has not moved an inch in that time. I can only fuck the girls so many times before I am bored while the content I do want to build up to never seems to come up. Same issue here. We had all our fun with the randos and static NPCs here that we can. New species, new ways to have sex, etc. will not address the core problem that we have made zero progress in the main game in years. Side stories at this point do absolutely nothing to retain interest, I want the game to get on with it already.
Inversely, one of my favorite games here is Monster Girl 1000 because I got plenty of side content while the main game consistently got updated to a point where it hit a definite end. Every update seemed focused on progressing this goal and brought something new to the main story while allowing me to manage all the girls appropriately. As a result, I never saw an update that made me think "Oh boy, I wonder how this one will waste my time."