Make Unique's usable through upgrading

The problem that every unique item has is the base stats are just too low. Only some rings and belts even come close to viable because of this, and it makes it so that all of these awesome looking art pieces go completely to waste.

I say we need a system that upgrades unique item base stats. The vision for unique items is to be weaker than rares but enable special mechanics for builds, and with usable base stats this is still the case.

If you wear a unique chest piece for example, whatever benefit you are getting you are trading away elemental resistances, max health, valuable base stats that a rare has. You should not have to trade away armor, evasion, or shield in such vast quantity as to effectively not be wearing a chest piece.

I think the best way to fix this is a system that upgrades unique's base stats to appropriate levels. For example pillar of the caged god is a quarterstaff doing 9-18 damage, allow us to upgrade it to 53-111 damage. That is the damage of its expert base counterpart.

The cost of upgrading could be: Gold, a duplicate unique, a new currency item, a trial with an altar at the end, etc.

D2 had this feature through cube recipe. D4 has all uniques drop at highest ilvl when you do max level content.
I don't know why GGG insists on keeping outdated item design where certain fun weapons (and armors to some degree) are not viable in the endgame because of their low stats.

Agreed, all Uniques are kinda pointless, their stats are rather bad, and i am yet to find a unique that i want to use after good 100 house in the game.