- Sept. 28, 2017, 5:43 p.m.
I don't think it's about their culture not being "primitive", it's more that when you play a Human or a Blood Elf, or any other race for that matter, your character comes from a specific "faction" within that race. This lends them the ability to choose what they want to "be" when they grow up, but only insofar as what that particular society offers.
Playable Humans are always from the nation of Stormwind. Playable Blood Elves are always from Silvermoon. While it's possible for there to be "break aways" in the story and for members of those races to join "opposing factions" and learn new skills, that's not something that's on offer to player characters.
If those classes were ever added to those races, I would expect specific backstory to be created for how those races adopted those techniques and rituals, such as with gnome hunters "creating" and taming mechanical beasts.