I can understand the frustration/disappointment—and I definitely agree that the game has a lot of untapped potential!
On the one hand, I do yearn for new projects and challenges, after working on the same game for over 4 years; so that's definitely an issue of motivation. On the other, however, the more complex a project becomes, the more work it is to add new things on top of it, too: For that reason my goal was always to make a small—but polished—experience. In that sense, the project has achieved all it has set out to be (and more)... which is not to say that it doesn't have a lot of potential to be more than it is, of course!
Then there's a whole business-side to this, too, unfortunately... Wish that wouldn't factor into it, but that's just how it goes, I am afraid.