Another article came to my attention just now on the issues with the production of the films which seem to suggest it was less "Vague Recollection" and more "Rushed Production" (although surely they at least had the book as a guide?):
http://www.theverge.com/2015/11/19/9...le-explanation
Long story short, as
Faramir Jones posted on the previous page, there is indeed a special feature on the Part 3 Blu-Ray which discusses the difficulties of the production.
This seems like the perfect promotional opportunity to me: "Only by buying The Battle of the Five Armies on Blu-Ray will you be able to discover why the film is so terrible!"