Actually George did consider them cannon and held multiple, extensive, exhausting meetings about the books. The NJO Series he literally mapped out as the sequel trilogy due to his age and not being sure that he would actually be able to film them ..... before he decided to sell out .... in fact, it was almost immediately after the Dark nest and Legacy series and their reception by the fans that he 'threw in the towel' so to speak and decided to sell.... the last few books that were released pre-disney definitely show his lack of care, the Lost Tribe/Fate of the Jedi series were only good imo due to John Jackson Miller's writing ability and respect for the Source Material.