That scene between Boromir and Aragorn is needed.
In Rivendell, we see the Aragorn is afraid that he has inherited Isildur's weakness for power. Arwen tells him that's not true.
Then in the extended scenes, we see that Aragorn is relunctant to be king because he has never been tested to see what strength lies in him. Oh, yes, he's done brave things... but this is a testing of character.
At Lothlorien's parting, Galadriel says the timing for testing, for choosing has come. Aragorn must make up his mind to rise about his fathers failures or to sink lower.
Then comes the new scene between Boromir and Aragorn. Boromir is right. Aragorn is judging all men on past failure. Because Aragorn believes that all men are weak. That's why the ring can't go to Gondor. He sees in Boromir everything he believes about himself...
Until, he passes the test and lets the ring go. There it was... all he had to do was take it. The ring was calling his name. He let Frodo go.
Boromir's death scene is so poignant -- now that all the shadings and nuances have been woven into "my brother, my captain, my king".
I think Boromir meant to say,"...my Ring." ;^)
"[Tolkien] described it as a romance and a saga," said Walsh. "The big challenge was to find a level of engagement for the audience. A saga really doesn't allow that. Like Aragorn, who is a classic saga hero. He really has no interesting psychological makeup in the book, no emotional depth. Yet the audience must connect with him."Link to the rest of the interview."We had to dig a little deeper beyond the mythic hero," said Jackson.
"Aragorn was caught between his role in the quest and his kingship," said Fran. "He understood that power corrupts and so to embrace it would be dangerous, especially to him."
"He realizes the power of the ring is evil and that his forebears were ruined by it," said Jackson. "He was raised by elves, so his attitude might well have been that this race of man is weak. He might doubt whether men can rule the world."