I agree,
CoD, that movie-Grishnįkh was suited to the movie-audience. However, I can't see how movie-Treebeard was more suited. But that's a whole new topic (of which I lay claim to

).
The popcorn-munchers enjoy their hungry bloodthirsty monsters. That's why they made Grishnįkh into a slobbering beast, rather than a tricksy fiend. That and time constraints. They were probably able to chop off a couple of minutes by doing this. But then, the extended edition...