Excellent point that you can hide completed quests. What as the point of developing that feature if you now have to do Loremaster 8 TIMES!
Plus they made it you can unlock any item so long its not a class item from loot. Logically that should follow with quests.
Plus the retroactive quest unlocks I feel was also mentioned in Blizzcon.
We need a response!
Edit: this is the only other response. “CS is not devs but confirmed not unlocking all appearances not a bug” https://eu.forums.blizzard.com/en/wow/t/transmog-quest-reward/527201/20