Diadem sorta already has this already, but it fails in this regard because the primary objectives of Diadem are battle oriented.

You could have a new class of dungeon where bosses block access to DoL nodes, allow unlimited job changing, no drops from the mobs themselves and a strict time limit. More valuable nodes could be deeper in the dungeon, making it more difficult to get to in time but with better materials.

The materials would also need to be unique (not available anywhere else).