Q: Are the Warcraft and World of Warcraft RPG books considered canon?
A: No. The RPG books were created to provide an engaging table-top role-playing experience, which sometimes required diverging from the established video game canon. Blizzard helped generate a great deal of the content within the RPG books, so there will be times when ideas from the RPG will make their way into the game and official lore, but you are much better off considering the RPG books non-canonical unless otherwise stated.
I already got this vindication at Blizzcon from Metzen himself, but it's nice to see it corroborated by the other developers.
Suck it, Wyrmrest Accord, you self-important fucks <3 I cannot fucking tell you how many dumbass discussions I got dragged into over stuff in these books, always over some douchebag losing their shit in the WrA channel (or elsewhere) because someone wasn't playing according to random 'fact' A in those godawful books.
The only thing worse than being an elitist is being an elitist and fucking wrong.