Regardless of what the expanded universe said, I think that George's script overrides everything. Although I may not agree with some of his choices, I think that he has the final say. IMO back then he wasn't considering continuing the Trilogy so he allowed licensing to go on, but has since decided to (obviously) continue his story.
Think of it this way, if the Matrix came out, and they didn't make sequels to it for say 10 years, but in that 10 years they allowed the same type of expanded universe type stuff to go on, and some fantastic novels and books came out of it with incredible stories. Then say that parts 2 and 3 came out exactly like they are now. That's the best analogy I can come up with for it.. just my opinion.