In the latest Harvest Moon and Story of Seasons games, mining has been reduced to striking a mining node (usually a large rock marked with an "x") for a few gems a day. Mining is now too easy and not a challenge at all. No longer are we stocking Elli Leaves for a trek down 100+ levels of the mine.
Some users may welcome the change, but during long Winters where lakes are frozen over, trips to the mine were a welcomed time waster. The mines were similar to mini-games, where you had to trace your path to the next stairwell or destroy the hazards that would sap away your stamina.
Reintroducing mining would bring more activities back to the series. It would make upgrading tools or creating accessories more challenging, too.