Problem of a sandbox is that balancing the "grinding" is usually quite some work and usually results in some trial and error. Also a sandbox also has the problem that many people fear they are missing some content due to not finding the correct places at the correct times. Finally, sometimes it is also quite hard to figure out what to do.
If all these things are done correctly, (like in my opinion Lunars Chosen has, only the photoshoots I think I had one time 1 photoshoot that was hard to find), then it is really awesome and I love it more than a VN. But if already 1 aspect is lacking, then I prefer a VN. So with that also directly an amazing compliment to PTGames, along with the beautiful renders and diversity of the women, the amazing fun fantasy story line and that club that is just so amazing, it's even fun to hang around when you finished all the content