This change was important.
I think that high level enemies and especially town guards and military should have access to the same metals, woods and fabrics as the player. A knight or professional warrior fighting with copper weapons and armor is just stupid. They should have access to the best materials.
I think changing the colors of the materials on the sprite in the inventory and overwordld icons (eg. an adamantine hammer looks green in the inventory and on the overworld, white leather armor looks actually white, a spider silk tunic looks white) would be another good idea.