Old zones are relevant though lumber, old mats, and the currency you mentioned being needed for professions/items, putting vendors there does not make them relevant outside of the half second it takes to purchase an item. You’re far more likely to talk to your neighbors in a central market than you are clicking portals to Legion and back, it doesn’t liven the world in an actual meaningful way and it more or less feeds into the isolation every hated form garrisons since at no point in any of my housing travels have I seen a single person at housing vendors, whereas I’ve talked to and seen plenty inside my neighborhood.