Classes played smoothly in Legion because 1/3 of your skills (including cool passives) were tied to the Artifacts. Once they were removed, they left a gaping hole in most classes/specs' rotations, which was one of the main complaints about BfA gameplay-wise. And while this "unpruning" of SL is a step in the right way, there is still a long way to go until classes play as fluidly as in MoP or even WotLK.