One conclusion that may reasonably be drawn from the movie’s “adaptation” is that the screenwriters think the decision to go to war cannot be the result of careful deliberation. It must be the result of a hasty action, which itself is done as a result of passion (usually anger).
Or, at least if the screenwriters don’t believe this, they believe that audiences will not find the book’s version convincing. But that seems to be because modern audiences do not find the method employed by the Ents of the book as a plausible way to make decisions in general. That is, the majority of people make decisions based on an overwhelming feeling. Perhaps acting decisively after careful, lengthy deliberation is too foreign to many moviegoers today.In this, I think Burglar is exactly right. But there is more to be said: the change in the Ents is one of a number of changes that indicate Jackson thinks characters are more interesting when they are conflicted about their decisions (I’m going to presume for a second that Tolkien thinks the Ent’s decision is the right one).
While most of Tolkien’s good characters consistently do the right thing without doing the wrong thing first, Jackson rejects this idea. The Ents decide to not go to war. Most obviously, Faramir takes the Ring back to Osgiliath. Frodo rejects Sam when entering Mordor.
Such changes reflect, I think, the “spirit of our age” and the blurring of lines between right and wrong. In Peter Jackson’s Middle Earth, acting deliberately and decisively for goodness is only possible when the evil is seen, touched, or tasted. Only when Faramir sees Frodo nearly give the Ring to the Nazgul does he realize his folly. Only when Treebeard sees the destruction of the forest firsthand can he respond as he should have in the first place. As a result, Jackson’s characters demonstrate far more angst than Tolkien’s.
Peter Jackson’s movies are great films. But they ultimately reveal more about ourselves than about Tolkien’s books.