Correct me if I'm wrong but isn't the Warcraft storyline 10 years in the making?
Since when does sheer length and history = better?
Besides, I saw this blog once pointing out all the individual faults in the W3 storyline. They're pretty major because the whole saga was made by a huge number of people at different times.
And when I played WoW I never saw any reference to any of the books, just WII and WIII...