Of course it is lack of healers but it has nothing to do with the strike. There was two brand-new DPS roles added to the game in the expansion, many players have been trying out these roles which has caused queues to be longer for everybody else. If Dawntrail was to have added a healer role then it is guaranteed that healers would be the one sitting in queue for 12 minutes regardless of any strike. The forum is such a small percentage of the player-base and even then not everybody agrees with (or can be bothered to) strike.