I agree with much of the above, but something else to consider, the kind of story Tolkien was writing: a mythic history. He wasn’t trying to maximize the tightness of the plot, or the amount of action or melodrama. As in a real history, things exist and do stuff that may be inconvenient for particular storytelling purposes. And Tolkien wanted to capture that feel in the Lord of the Rings.
I think that’s what the movies fail to capture as well as Tolkien’s writings.