I know this question sounds either ignorant or sacrilegious but Peter Jackson clearly added a lot of material and characters that don't exist in the original Hobbit book, either from other Tolkien material or simply out of thin air.
Are there any plans to re-novelize the films the way they were actually made?
If not, what are the reasons? (Legal problems, fan-backlash, etc.)
I know this question sounds either ignorant or sacrilegious. You are wrong. It sounds both. Now seriously (and apart from the answer), it is not unheard that in the process of adaptation to film changes are made to the original narrative, but that those changes are enough to consider the result a different piece of art would be quite exceptional (and would require just than copy&paste of some characters from LoTR).