The game's structure as well as how the fights are designed pretty much make any meaningful support impossible to implement. Even our sparse CC options stop working in 50 content for the most part and you don't need it in the overworld. They would have to redesign combat from the ground up again to make space for a pure support role and then there would be the balance issues which after 3 expansions now I think they just don't have the chops to handle that if they were to try.