Evokers should be able to Transmog Cloth and Leather items. They were just added to the game, the selection of items they can Transmog is very slim compared to other races. On top of that you can only see transmogs on Visage form since the Dracthyr body shape is too different. I’ve just went on an 3 hours transmog collecting trip on Pandaria and realized ONLY 2 head pieces were collected (mail), every other piece (cloth and leather) cannot be collected. So basically we are limited to a very small amount of old content.
this happens with every new class, DH had no tier and all gear before legion was limited and looked trash if it wasnt tier.
Monk had no tier before MoP and all leather before it looked trash except for a few pieces.
DK got away with alot, alot of the tier sets were rereleased as either pvp variants or dungeon drops.
Dracthyr how ever has basically no tier appearances. Adds that they can only see their shoulders and none of the shoulders, even the tier set work with Dracthyr as a whole. The armor they offer as barbershop doesnt actually match any of the tier shoulders or any shoulders. You are stuck with either turning your belt and shoulders off and using the barber shop ones, or just not using Tmog. Its kinda trash