The Bombadil/Barrow-wight sub-plot was easily left out. It made for a good read but it's exclusion didn't detract from the overall story.
The Scouring of the Shire however is a major part of the story and ends the War of the Ring back in the Shire amongst Hobbits. Remember the LotR is a story about Hobbits. It says so in the prologue. And JRRT actually stated the TSofS was one of the earliest parts of the book to be written.
To my mind the movies focused too much on Aragorn/Arwin which was only a sub-story in the books.
I did enjoy the movies - however I feel PJ, et al missed the overall point.