The reason for this is simple: Most players don’t need a lot of gold or care very much about it. An active player might earn an income of a few thousand gold per week from sending followers on missions and doing World Quests that award gold. They might then spend most of that money at the auction house buying things like flasks and stat-buffing food to do raids and Mythic+ dungeons. Gold just isn’t a big deal for them.
Something to keep in mind as well is that this will make enchanting materials more valuable, since it is likely most players will now simply scrap their boe greens instead of getting them disenchanted. Also redundant dungeon/raid gear can be scrapped rather than traded to the (guild) enchanter in the run. Less stuff gets disenchanted, meaning there will be less ecnhanting materials, meaning their value will rise. All the more reason to DE rather than scrap as an ecnhanter.