Some specs are consistently good every patch while other specs get left in the dust for years. It sucks because you could be playing an okay-ish spec one day and then the nerfhammer hits you and suddenly you can't compete in raids or arena anymore. This is even more jarring when there are systems like AP and legendaries in the game which result in commitment to specs. Since Blizzard has an agenda when it comes to class balance, why don't they just reveal it so that people can avoid playing specs that are slated for gimping?
If there's a system like AP or legendaries in the next xpack or any other system that results in increasing spec commitment, Blizzard should reveal before launch which specs are expected to be good throughout the xpack and which ones are one-patch FotM wonders that will get nerfed HARD. No one likes playing gimped specs.