[Zigûr]

Something I think the filmmakers overlooked is the fact that Aragorn actually does have a small character arc in the book, appropriate for a secondary character (which he is).

For instance, after the passing of Boromir, Aragorn expresses self-doubt about his ability as leader: "Since we passed through the Argonath my choices have gone amiss." He does undergo a process, motivated by the loss of Gandalf in Moria, of understanding more seriously what leadership involves and the responsibilities he faces by reclaiming the throne. As he becomes more confident, the narrative becomes more and more distant from his perspective; he becomes a "lofty" character, which is why, for instance, in the Paths of the Dead we see things from Gimli's perspective, as he is the least knowledgeable/confident character in the scene. In "The Departure of Boromir" we see things from Aragorn's perspective because he does not know what is going on (he was looking for Frodo, unlike the film, in which he is massacring Orcs) and is feeling insecure in his leadership of the Company.

Michael Drout gives an interesting lecture touching upon this narrative device, as Professor Tolkien uses it. The lecture can be found on YouTube if I recall correctly.

It comes back, I think, to the fact that the filmmakers turned Aragorn into one of the protagonists, when he's only a supporting character in the book. In the book, ultimately, the protagonists are the four hobbits, but as diminutive folk not wholly inclined to action and derring-do they can't be the only heroes in a Hollywood film, so Aragorn's role is altered. It's one of those things, in my opinion, that shows why the book was unsuitable for the "Hollywood treatment".