Arwen on the poster

Huh. Let's see: an advertisement for a movie puts a picture of an attractive woman in the poster. You're right - it's just plain crazy.

I think more than just being a woman/sex appeal it was that she was a more well known actor than most others. She was listed like fourth in the credits, even though other characters were obviously more prominent than her.

Also keep in mind that when Liv Tyler was first cast, Arwen was supposed to have a much larger role in the story.

Originally Arwen and Elrond were going to travel to Lothlorien to visit Galadriel. Arwen would look in the mirror and see Aragorn dying at Helm's Deep and that is what prompted her and her father to ask for troops to go to Helm's Deep. Arwen would have then gone to fight in the Battle of Helm's Deep, which would have made her present during the entire film's third act.

Had the scriptwriters not rewrote Arwen's arc due to fan backlash, Arwen would have likely been more involved in the plot of The Return of the King.

But as we all know they decided to cut all of Arwen's scenes at Helm's Deep (she could still be seen briefly in the background after Gandalf and the Riders of Rohan save the day), and they came up with a new story — more faithful to her character in the — in which she contemplates her future of living on after Aragorn dies.

Would you rather stare at Liv Tyler, or Gollum?

Look- it's trying to think!

Gollum on the main movie poster just doesn't have that same effect as Arwen on the poster.

While she was not quite as prominent a character in the books, she was given a larger role in the films, and the original plan was for her to go to Helm's Deep to help out the army there against the Uru-khai, but the idea was scrapped during the post-production period.

So there are a lot of cut-scenes of her doing stuff at Rivendell, and advertisements of her being shown prominently, but due to changes in plans, you don't see this in the final cut, not even the Director's cut.

I learned about this at the AlleyCatScratch website where they had pages on all the costumes in the films, including the burgundy robe Arwen wore when fighting at Helm's Deep in the original movie plan.

Because at the time she was the hottest thing

Hasn't anyone ever told you? There's an old Hollywood trick that's been used, probably ever since the 70s, maybe even earlier than that; where if you have a predominantly male cast, one way to hook in female viewers is to put include one, well-written female in the group. It's worked for decades.

While Arwen doesn't play as prominent a role in the books as she does the movies, it's done carefully so that she doesn't take over the cast or go so far outside her original character as to offend the original Tolkien fans that read the books long before the films came out. She still remains feminine, and not in every danged scene, stealing the spotlight from the characters that actually deserve it. In fact, there were many, many scenes cut from both the theatrical and extended editions of the films with her in them, because they didn't add anything to the story, and it was mostly a small subplot about her trying to help Aragorn from afar.

She also presents a romantic element to the series that hooks in a lot of people, because it shows a prominent character like Aragorn having a strong motivation to save Middle-Earth, because he's saving Arwen as well as all the good people of Middle-Earth.

Liv Tyler was most certainly a big star at the time. Everyone at the time remembered her as Grace from "Armageddon." To see her beautiful self with elf ears and lovely costumes was the chef's kiss in these movies.