My guess is a lack of demand.

People use tomestone gear until 75-76.

Some people don't gear up at all past 70 since you can just do PotD, HoH and Gangos along with roulettes.

People doing the MSQ get their gear from quest rewards and dungeons.

Also gear above level 70 can't be crafted in two actions. So if you are a lazy crafter you don't want to waste time making those.

I think the only potential demand is for crafting leves and a lot of people just do the facets or Firmament instead.