Class design was awesome ??? Have you even tried to play arenas or bgs ? Playing currently on Blacrock and retail, I can tell you that class design is in its worst state.
Retrded class design began at cataclysm with the destruction of many classes skillcap (hello warrior, hello rogue, hello hunter, hello mage) and the homogenization of everything (every healer has a defensive magic dispell, every dps has a self healing ability or cd, everyone has a panic button...).
In comparison of what we have nowadays, Cataclysm still looks good gameplay-wise though. It's gone brutally worse at WoD, and completely dumbed down at Legion with the suppression on top of that of many core abilities to make them fcking talents. Plus the introduction of the most retrded class ever : demon hunter (3 buttons for damage, infinite mobility if not rooted, welcome to Legion).
The PvE is pretty good though indeed, Mythic+ is a good add, and raids are enjoyable so far