It's useful for equipping a follower if you don't have Smithing perks for heavy armors or the Dragon Armor perk and you use a follower that has Heavy Armor as a primary skill because you can equip them with smith improved Daedric Armor and Shield that will get them past the 567 armor rating needed to get the maximum physical damage resistance of 80%.
I equip Lydia with Daedric Armor, Shield, Bow and Sword. Her armor rating is 619. As a result of the armor rating and the enchantments I put on her gear she can solo a Giant and 2 Mammoths so to me it was worth it.