Ahh "The Scouring of the Shire"...
Which is a fairly big part of the Hobbits' story.
Well, that's the difference between writing a good book and making a watchable movie. If you'll recall... The main story is about a ring and the ring bearers and the mission to rid middle Earth of its evil. Side story was the restoration of the King to his rightful place. As a movie it was already plenty long and the main story was already told. The scouring would have been small in scope by comparison... But a lot of screen time. It was enough movie already. And Jackson didn't ignore it completely... He gave space to the scouring when Frodo was using Galadriel's mirror.