That's Ent-ertainment

[Elladan and Elrohir]

I think the reason they changed this was partly to show the growth in Pippin's character, as has already been said, but also to make the point that there are times to make peace, and there are times to go to war. They really point this out in the Directors and Writers commentary. You have Treebeard going, "Well, it's not a big deal to me; plus, how are we supposed to do anything against a force like that?" But the Ents HAVE to go to war, both for the sake of the story and because it's the only moral choice to be made.

I'm not sure that I like this change. I understand pretty well why they did it, but it makes the Ents (especially Treebeard) look stupid and unlikeable. If they kept it the way it was in the books, I think it would have worked just as well -- and they still could have found a way to work in their point about the moral duty to fight Saruman.

It's interesting that this movie was released in December 2002, and the U.S. went to war in Iraq in March 2003. Not to suggest that PJ and Co. are making political statements, but the timing is nonetheless intriguing.