It is maybe because the updates are sparse. Also, being a story oriented sandbox doesn't help. People that go for Sandbox, couldn't, in general, care less about story, and vice-versa. It was also plagued by a lack of warnings about the End of Content, leading to player frustration.
The game is good. IMHO it would be better in VN format since the story is rich and well written with great characters, so much so, that the Sandbox feels tacked on and completely pointless.
I would say, play it and judge by yourself. I think that in spite of it's shortcomings it is still worth it.
Peace