Arwen was only swapped for eye candy, she plays a minor role in the books, on the other hand Glorfindel is a high elf on a level plain with Elrond, who gets an even smaller mention in the books, it is Arwen who raises the fords of Isen, Gandalf gives himself credit for the waves appearing to be horses.
I agree Osgiliath is well overplayed, an error on Jacksons part, there were other worse gaffs or alterations, whichever way you want to look at them.
1) Regarding Arwen raising the fords of Isen, not true. It is Elrond who does that, Arwen does not make an appearance yet.
2) Regarding Glorfindel, he is not on the same level as Elrond. Glorfindel is a "simple" warrior and he plays the same role to Elrond as he did to Lord Turgon. Advisor and Military Shock Factor Trump Card. Everyone embedded in the darkness shits themselves when they see Glorfindel in all his light.
Regarding Arwen, she does not play a "minor" role in the books. She does not make a direct appearance much, but her existence and character is crucial to the plotline and she constantly appears in reference or in background passing without a direct link. Put it this way, without Arwen's existence the "good" side loses the war and Sauron becomes victorious. Why? Because Aragorn wouldn't have showed up.
On the top layer, we are introduced to Aragorn as this confident, brash hero who is desperate to become King and will tell anyone and anything that he is the rightful heir of Elendil and Isildur. But why does he want to become king so bad? Well, 40 years prior to ROTK, Aragorn already had the perfect opportunity to become King. He had the command of the entire court, Ecthelion favoured Aragorn over his own son, Denethor and Aragorn could easily have taken the throne then and there. Instead, he goes wandering around Harad, goes to Mordor and then heads back to Lothlorien before going to the North and residing with the Dunedain for the next 35 years. Why?
Well, the answer to the question, to put it in modern terms, is that Aragorn was a ****. Edit For some reason S1MP is filtered out.
In the first half of his life, he meets Arwen and Elrond tells him that she isn't good enough for him and that he must do something great to ever catch her attention and that he is too young. He basically sets out immediately and does "great deeds" to prove himself.
‘‘Aragorn, Arathorn’s son, Lord of the Dunedain, listen to me! A great doom awaits you, either to rise above the height of all your fathers since the days of Elendil, or
to fall into darkness with all that is left of your kin. Many years of trial lie before you. You shall neither have wife, nor bind any woman to you in troth, until your time comes and you are found
worthy of it.’’
By the time he enters Lothlorien, Aragorn is "weary" of the world, and lost most of his motivation. He doesn't really have cares for the chaos of the East and he sees much suffering and destruction. He doesn't have a desire for power despite basically being the most popular man in Gondor as Thorongil. All he wants to do is go home to Imladris and live a simple life before going back to the nomadic ways of his people.
‘Thus he became at last the most hardy of living Men, skilled
in their crafts and lore, and was yet more than they; for he was
elven-wise, and there was a light in his eyes that when they were
kindled few could endure. His face was sad and stern because
of the doom that was laid on him, and yet hope dwelt ever in
the depths of his heart, from which mirth would arise at times
like a spring from the rock.
‘It came to pass that when Aragorn was nine and forty years of
age he returned from perils on the dark confines of Mordor,
where Sauron now dwelt again and was busy with evil. He was
weary and he wished to go back to Rivendell and rest there for
a while ere he journeyed into the far countries; and on his way
he came to the borders of Lorien and was admitted to the hidden
land by the Lady Galadriel.
But in Lothlorien he meets Arwen again, who loves him back after 29 years apart and they become engaged. Aragorn goes back to Imaldris to ask Elrond for her hand, having "proven himself to her." But Elrond says this:
‘ ‘‘My son, years come when hope will fade, and beyond them
little is clear to me. And now a shadow lies between us. Maybe,
it has been appointed so, that by my loss the kingship of Men
may be restored. Therefore, though I love you, I say to you:
Arwen Undo ́miel shall not diminish her life’s grace for less cause.
She shall not be the bride of any Man less than the King of both
Gondor and Arnor. To me then even our victory can bring only
sorrow and parting – but to you hope of joy for a while. Alas,
my son! I fear that to Arwen the Doom of Men may seem hard
at the ending.’’
‘So it stood afterwards between Elrond and Aragorn, and they
spoke no more of this matter; but Aragorn went forth again to
danger and toil. And while the world darkened and fear fell on
Middle-earth, as the power of Sauron grew and the Barad-duˆr
rose ever taller and stronger, Arwen remained in Rivendell, and
when Aragorn was abroad, from afar she watched over him in
thought; and in hope she made for him a great and kingly stan-
dard, such as only one might display who claimed the lordship
of the Numenoreans and the inheritance of Elendil.
Basically, Aragorn had lost motivation, but Elrond dangled his daughter's hand in marriage as a carrot for Aragorn to become king. Without this motivation, Aragorn would have long lived his life like the previous Chieftans of the Dunedain or married Arwen and lived out his life in Imladris. Essentially, Aragorn's entire motivation after 2980 T.A was to become king so he would marry Arwen.
This is alluded to multiple times in the books, with references that are hard to understand:
When the Gray Company arrives and Halbrand passes Arwen's message, it is this:
It's not "Your hope of being king", its, "Our hope of being together."
It is Arwen's banner that turns the tide of Minas Tirith. When Halbarand raises the banner into the air, the Gondorians and Rohirrim's morale is raised immediately because their reaction was, "Holy fecking shit, Elendil has returned YESSS!!!!"
Orcs reaction was, "What??? But how can this be? His line ended 800 years ago!!"
‘It is a gift that I bring you from the Lady of Rivendell,’
answered Halbarad. ‘She wrought it in secret, and long was
the making. But she also sends word to you: The days now
are short. Either our hope cometh, or all hope’s end. Therefore I
send thee what I have made for thee. Fare well, Elfstone!’
And Aragorn said: ‘Now I know what you bear. Bear it
still for me a while!’ And he turned and looked away to the
North under the great stars, and then he fell silent and spoke
no more while the night’s journey lasted.
For example, when Eowyn begs to go with Aragorn to go with him and Aragorn rejects her, she complains that why is Aragorn allowed to do what his heart desired but Eowyn was not. Aragorn replied that his hearts desire was not to fight this war but to be with Arwen:
‘Only so can I see any hope of
doing my part in the war against Sauron. I do not choose
paths of peril, E ́ owyn. Were I to go where my heart dwells,
far in the North I would now be wandering in the fair valley
of Rivendell.’
When the war is finally over, but after a few months Aragorn falls into despair because he does not know what happened to Arwen. He literally laments that everything he did was for nothing and that what use is there in being king if she is not here. Only when he discovers the seed of Nimloth does he feel hope again:
Note that his implication here is, "If Arwen does not arrive, the line of kings will fall because I will not have children or marry anyone else; nobody else will be queen."
‘But I shall die,’ said Aragorn. ‘For I am a mortal man, and
though being what I am and of the race of the West
unmingled, I shall have life far longer than other men, yet
that is but a little while; and when those who are now in the
wombs of women are born and have grown old, I too shall
grow old. And who then shall govern Gondor and those who
look to this City as to their queen, if my desire be not granted?
The Tree in the Court of the Fountain is still withered and
barren. When shall I see a sign that it will ever be otherwise?’
There are plenty of other references signalling the importance of Arwen, such as Aragorn naming his horse Roheryn.
Tl;dr Half of Lord of the Rings is one guys quest to get laid, becoming King was basically just part of the process of achieving his ultimate quest.
So to reduce Arwen's role as "minor" and "eye candy" just because she doesn't appear directly in the texts is wrong; without Arwen, Sauron ultimately wins.
