That way we could more easily have gear that levels with it while also chasing upgrading rarity of ones we want better effects on?
I think this is going to require more elaboration. Currently rarity is not 100% linked to level as you can aquire rare, epic, legendary pieces and they would be level 1 and they can be leveled up to their max rarity.
Are you suggesting another way to create increased rarities?
As in you can level a common to 50 and increase rarity separately whenever you want