Also, he basically destroyed the Ents. That was my favorite part of the book ("You have angered an elder power. The elder power hits you. You die.") Instead we

Also, he basically destroyed the Ents. That was my favorite part of the book ("You have angered an elder power. The elder power hits you. You die.") Instead we get Treebeard being basically a dummy sidekick for the hobbits, who realises late that Saruman is destroying the trees and then goes on a rampage.