Though I can't take that into consideration, but I understand what you are saying. The problem here is that Kishimoto has had his hands on other projects outside of novels, and movies. He has helped in video games, to where he stated in an interview this year that for Storm 4, he was helping out only with character designs (For PS Itachi, and Shisui), and he has worked on Mecha Naruto and Lars Alexanderson as well. I don't view any of these as canon, not even in the slightest.
For the Novels, he's the one who was asked to draw the covers, and illustrations. But comparing it the video games, he didn't really do much but offer his artistic work as the author. When it comes to the actual story line, I can't personally fill in the blanks because Kishimoto's opinion differs from the authors of the novel, by much. Take a look at the Boruto Novel; More BoruSara, more pairing moments, Boruto actually didn't cheat throughout every battle, and some of the other fights were different (just to list a few).
I only accept the Last as canon because Kishimoto wants us to, I'd do the same for the novels despite my feelings for it (like my feelings for the Last), if he outright said that they are.