For crafters, give them that last +5 crafting and allow everyone to craft 600-600. The roll itself can be Epic or Lenedary at like a 1:5 rate or whatever. This allows all the epic gear to already be umbral available and gives the market back to the Epics some.
For Mutations, have all the drops do the same. 600 drops with low Legendary rates. This nullifies the broken back end of the gear system, and since all this current gear is Expertise sliced to new players anyway, it doesn’t really cause a downward problem.
Now, at least all your garbage might be useful to someone, but nobody will pay 400+ Umbral on a 595 that looks good but the system screws you out of it.
Simple QoL change would go a long way in making this be far less bad.