This comparison doesn't really work, though.
That DH thing was Legion-only, and even then they were still able to show chest pieces from previous and new expansions.
Your solution would end up causing one of two things. They can only show non-tier Dragonflight mail chests that only show center pieces, so
1) they can only ever show chest armor from this expansion that has been edited for them and players wonder why other chest pieces arent showing up
2) you give the artists infinitely more work going forward as they have to adjust the armor every time for Dracthyr