RNG aspects suck - get a couple stubborn slots that won’t drop and you’ll tread water.
Also while leveling, pray your sands drop - my artifact was over 200 ilevels below my gear when I hit 80 as sands would not drop.
Power curve while leveling is smoother than MoP, and at cap not as punishing when fresh (fresh 70s in MoP would get one-shot by everything).
Not having cosmetics and power tied to the same currency is an improvement - though tying power to RNG is not.