It also would've been more compelling if they made their decisions themselves, showing how Middle-earth is uniting together against Saruman.

Source: https://www.cbr.com/the-lord-of-the-rings-harsh-realities-rewatch/

Of course, this made him a natural enemy to the Ents, who were responsible for protecting the forests that Saruman destroyed.

Source: https://screenrant.com/lotr-why-saruman-not-kill-ents-treebeard/

Saruman especially had devastated the forests of Middle-earth, and others were affected simply by the presence of evil that had resulted from Sauron's steady climb to power.

Source: https://screenrant.com/lord-of-the-rings-legolas-gimli-what-happened-after/

Saruman had either forgotten about the Ents' role as protectors of the forest or reasoned that they were too slow to act and too weak to stand against him.

Source: https://gamerant.com/lotr-how-saruman-get-isengard/

Saruman the White will amass Orcs 2 whenever its controller casts their second spell, which fits the blue-black amass control archetype and to a lesser extent, the white-blue "draw a second card" archetype.

Source: https://www.cbr.com/best-mtgs-tales-of-middle-earth-legendary-creatures/

This may be what Saruman had expected from the very beginning—that the Ents would come to Isengard and attempt gentler methods of stopping the destruction of their forests.

Source: https://screenrant.com/lotr-why-saruman-not-kill-ents-treebeard/