[Elianna]

I think Halbarad, Ellahir and the Dunedain would've been a good addition to the film.

Rangers have been introduced: They've already had Butterbur say about Aragorn "He's one of them Rangers. Dangerous folk they are; wanderin' the wilds." It would emphasis Aragorn's king-ness. If they brought the flag (or Andúril), it would give Aragorn something to use to show Sauron he is the King, when he looks into the Palantír (if the Dunedain got there early enough).

Here's how part of the scene could go, working in an ultra-cool line that was sadly left out of the movie: Someone names the group "Rangers" then Pippin or Merry asks "Rangers?! But Butterbur said they were dangerous?" Gandalf: "Dangerous! So am I, more dangerous than anyone you will meet unless you are taken alive before the throne of the Dark Lord himself..."

Maybe PJ thought a little band of Dunedain would look (to those who haven't read the books) too much like the little band of Elves showing up at Helm's Deep. But then the huge mass of chlorine (as my Chemistry teacher thought it to be) wasn't much different was it?

Personally, I like pretending that the elven smiths who reforge Narsil were Elladan and Elrohir, and Aragorn's standard bearer at Morannon was Halbarad (true, Halbarad died at Pelennor, but he was the standard bearer.) Why PJ didn't think of these loopholes, I don't know.