why don't people like arwen in the movie?

[Keeper of Dol Guldur]

It really depends on which movie. In the Two Towers, the very thought of her is what keeps Aragorn going. That was alright, it also elaborated a bit on how much Elrond cared for her, and even was integral. As far as the debacle that was her part in the Fellowship, I hate it. I know they were trying to establish her as strong in character and a strong part of Aragorn's life, his inspiration even, but would a father as protective as Elrond have let her ride against the nine, when he truly only let the most powerful of his house, such as Gildor or Glorfindel do that dangerous task. They had seen the light of Valinor, they glowed with it, they would not be afraid of the nine, but she had never even seen the nine, had never thought about rebelling and what I like to call "stealing Glorfindel's horse to steal the show." And I still think Glorfindel wouldn't have been "one more character," his inclusion would have shown the power of Rivendell, the fact that Aragorn was raised in Rivendell and had a good friend, and that Elrond had tremendous foresight and wisdom in sending someone like him. Not Arwen. He probably wouldn't have even sent Elladan or Elrohir against the nine. I really think elaborating Arwen's part takes away from Elrond's and Rivendell's power and wisdom. Other than that, I guess I have no problem with the romantic parts between her and Aragorn. But I really hope she doesn't steal away from her fellow elves to go give Aragorn his banner personally. I really only see that happening. Oh, and would she have put a blade to Aragorn's neck? I really don't think so, even in slight jest.