[Calenamarthiel]

I think Aragorn's more "vulnerable" scenes were added on to make the story appeal more to the modern audience. As we know, invincible heroes are not very believable nowadays, and the moviemakers definitely want their audience to believe in the stories they are telling. Hence, a more vulnerable and, sad to say, weaker Aragorn. It is true that in the books he almost never shows weakness, and he was never ashamed of his heritage, as he was shown to be in the films. But then, although his weaknesses were made more glaring in the films, they did not completely eradicate his heroic aspect either. I think the moviemakers just wanted a balance of humanness and heroism. Although I can't say that I'll every like that scene where he loses hope completely and kicks an orc's helmet when he thought Merry and Pippin were dead.