Part of the reason for doing the change now is probably due to the fact that this is the first new book since Snips, Snails and Dragon Tales. We got a preview of the style there - it's the 'enhanced stick' style used in the Julio story. Rich wants consistency within the book, so BRitF couldn't feature the new style without becoming a huge pain in the ass. So we get it now, at the time of a new book's start, a couple years after the style was previewed to us.