Roleplaying over the course of an expansion can take a few different forms.
We haven’t really heard much from the Knights of the Ebon Blade since the end of Wrath.
Monks are a recent addition to World of Warcraft, making their debut in the Mists of Pandaria expansion.
Warriors aren't exactly one of the most convoluted classes on Azeroth.
Mage roleplay has been ramping up over the past couple of expansions.
Hunter roleplay has never really been heavily focused on class -- mainly because the class as a whole didn't really have a ton of lore behind it.
Priests have been in the game since day one.
Everything that is, is alive.
They aren’t practitioners of flashy magic, architects of some grand, universal design, nor members of any kind of army set on defending the universe.
Paladins have always been warriors of the Holy Light.