The demand is seemingly there for such a workshop (considering that it felt like that out of 10 people 5 got banned because of the launcher). Far too time consuming and costly, but if you have a group of modders who decide that this would be worth their time and effort…well…why stop them? You basically go the Bethesda route: Why fix it yourself if you have a community who will do it for you? We all know for example that Blizzard will never make the hair visible on older armor pieces. These mods could potentially be anything: From updates and retextures of old armor sets, the fixing of clipping issues with armor and weapons, visible hair for helmets, maybe a new hair-style or even skin color if you feel really fancy. Obviously these mods would not influence the gameplay in any meaningful way and they would be client-based meaning only you can see the change (unless other people have the mod installed as well).
Players can submit their own mods for the game which are approved by Blizzard. So the basic idea is basically to create the equivalent of the Steam Workshop for World of Warcraft. With the discussion about the model changes still going on I was asked to open a new thread about this particular idea.