Ah yes but there is always the possibility of more Black Sheep. My wife found out one of her ancestors was in gaol the day he became a father. Turns out when he heard the news he went down the pub to celebrate, got into a fight and was arrested. There is always a story.
I would say not including the Scouring of the Shire at the end was a mistake. If that's the worst thing they did, that's not bad. They got much stronger when they made the Hobbit movies.
I can see why they left it out. The film's ending was already running really long. For me it was the undead army's role in the battle that was a mistake. And the fact that the Mumak's hide/skeleton seemed unnaturally weak.
True, the army of the dead in the book couldn't physically harm the living. They scared the enemy army away. A ruse they could only pull once.
Which is a much better solution. The movie version was completely OP, an unstoppable force that could not be harmed and obliterated everything before them. Their actions overshadowed the charge of the Rohirrim a few minutes prior.