Yes, I agree with your idea. The gameplay and replayability of this game are excellent, and if the development team increases their investment in it, it would be a win-win situation that we would both be happy to see.
The mod concept is actually quite simple; the developers only need to provide a port to serve as a foundation for players to add their own content. If they are worried about any "unexpected" issues, they can simply provide story mods and image mods.
Regarding game-level CG images, I don't think this is a troublesome issue. It's clear that the game's CG images are AI-generated pixel art, which requires AI quality rather than artist quality. And in my opinion, the quality of the images you've provided so far is already sufficient for the game's needs.