I don't use the images after I move the files to my computer, but I don't see a reason to skip their generation. The app uses them, and makes it fast to scroll through the images for a target in the app to see (in general) if there's any clouds, trees, etc. that ruin at least the center of the image. When I move all the files to my computer, I'll delete them. The jpg files are less than an additional 25% space, and every OS out there will allow you to find by extension when you want to delete them. They really don't use enough space on the seestar itself to make any real difference, as the seestar easily has enough space to get a full night (and some extra) with everything there.
If you're forgetful and running out of space on the seestar, you can move the files from the device from the SMB share over the network while it's still capturing. Of all the feature requests here, this one makes the least amount of sense.