There is a major undercurrent in the books that is essentially Tolkein's lament over what happened to Europe, and the English countryside in particular during the two world wars of the last century. The reason the scouring of the Shire is so important is that how the hobbits felt when they returned to the Shire and saw it so changed represents how Tolkein felt after he came back from fighting World War 1 and found his hometown, and many other towns in the English countryside overtaken by industrializing forces. In that chapter he's lamenting the loss of the "simple" agricultural life that people used to live with the new industrial life that was forced upon England by the war fever that swept Europe.

I think that PJ is doing a wonderful job of telling a great good vs. evil story, but he's taking out a lot of the points that make the Lord of the Rings great literature as opposed to just a good story.