Cluin, it's not true that Saruman's voice has been ignored in the films. In FOTR, he uses his voice to change the weather (and Legolas hears "a fell voice on the wind") while the fellowship is on the mountain, and in TT Aragorn specifically tells Legolas and Gimli not to let Saruman speak because he can put a spell on them. (Of course, it was Gandalf and not Saruman they were meeting, as it turned out). One of the major reasons why they picked Christopher Lee for the role was his voice!

It's true that the scouring of the shire was never filmed and will never appear in Jackson's films, however cynical you wish to be about getting squeezed for an extra thirty bucks. Jackson has said (I believe to Newsweek) that he never liked that section of the books and therefore never scripted it in; it was out from the very beginning. They did, however, film a scene in which Grima kills Saruman, and that WILL be on the extended version of ROTK.

As to the war being a sub-plot, I don't think so. Tolkien's choice for the title of Return of the King was The War of the Ring, but publisher George Unwin overrode him. (In either case, the title is about the war and its consequences, not the quest; a title like "the destruction of the ring" would be more quest-focused.) As a veteran of the Somme, Tolkien's experience of war was one of the major ingredients he used in his fiction; even The Silmarillion is about a war. Certainly LOTR is also about a quest, but the fact that in TT and ROTK Tolkien splits the action into Book 1 and Book 2, with Book 1 recounting the war and Book 2 recounting the quest, suggests that they are equally important parts of the overall story. Jackson happens to be a war film nut, and seems to be focused on that part of the story. But, in his favor, I must say that the slowest portions of the book are the endless meanderings of Frodo, Sam and Gollum looking for the cracks of doom...