One of the exciting things about mining is the element of surprise and the exploration of the unknown. I think it takes some of the fun out of it when you can instantly see all the nearby cave systems as soon as you go down a minehole. It's also quite abusable when you can hop into a cave near a village to see what their underground setup looks like and mine directly to it
I dont know how difficult it would be to implement but a minimap fog of war would be nice where map is darkened unless you have already discovered that area