(Don't play WoW anymore so I can't post on the official forums.)
Right now there seems to be a number of problems with the group disenchanting option being introduced. the first can be seen from the patch notes which says: “Disenchant” works exactly like “Greed” except if a player wins the “Greed” roll, they will receive the disenchanted materials instead. Seems like in this case the “Greed” roll serves no purpose. There needs to be a priority system in place with “Greed” having priority over “Disenchant”. That or it might be a good idea for only “Need” and “Greed” to continue to remain as the two looting options with the player who wins the “Greed” roll given an option to have the item disenchanted.
Of course the other major problem is that it seems a lot of enchanters dislike having one of their abilities being used for the benefit of non-enchanters without being compensated. They see it as unfair to single them out when other players with gathering professions in dungeons keep whatever they loot. I am not sure if the group disenchanting option is always possible or only possible with an enchanter in the group. It seems that one solution would be to make all items that need a gathering profession to be obtained could be made gatherable by anyone in a group who clicks on the item (whether skin, node or herb) with the winner being decided by an automatic “Greed” roll which the players could vote to turn off. This way all the non-enchanter gatherers who believe shards require a group effort will be also be satisfied as the items they obtain from gathering inside a dungeon also require a group effort.