I've been asking the same thing for the past few months. Not only for this game but also for many others.
Don't get me wrong, there are great sandbox games around, but they work because the dev put some thoughts in it.
They don't force you to grind for hours without anything new coming up, they provide hints or simply show on the map where new content is, so that even if the updates are on the smaller side, you at least don't feel annoyed because you needed to invest 2 hours to find 5-10 frigging minutes of content.
If all sandbox games were like that, you wouldn't hear a negative word about them from me, but alas too many go at it like lewdlab obviously did. "Let's start and see if it works and if it doesn't I try to fix it" which is an approach that might work in a straight vn, but not in a way more complicated sandbox set-up.
They don't think about how players will encounter new content, but plan based on the idea of a completed game.
There's more but that's all I can think of now.
I just wanted to make clear that there are several sandbox games I really like a lot.