We have a ton of great artifact models now, do you think it's time to allow us to transmog old legendary weapons? Outlaw Rogues already have an updated Thunderfury, Firelands Rag drops an updated Sulfuras, etc etc.
Even my favorite - the warglaives - are so pixelated and old looking compared to the new DH warglaive artifact skins. Seems totally reasonable to allow it now.
I'm basically just looking to use Shadowmourne.