Nos livros, os pés de Galadriel nunca são mencionados, então a questão é discutível.
Ela não aparece em O Hobbit (livro), e em Senhor dos Anéis ela aparece apenas em A Sociedade do Anel e brevemente em O Retorno do Rei . Sobre tudo o que sabemos sobre o calçado dela é que, se ela usa sapatos, eles devem ser brancos.
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O primeiro encontro da Irmandade com o seguinte:
On two chairs beneath the bole of the tree and canopied by a living bough there sat, side by side, Celeborn and Galadriel. They stood up to greet their guests, after the manner of Elves, even those who were accounted mighty kings. Very tall they were, and the Lady no less tall than the Lord; and they were grave and beautiful. They were clad wholly in white, and the hair of the Lady was of deep gold, and the hair of the Lord Celeborn was of silver long and bright; but no sign of age was upon them, unless it were in the depth of their eyes; for these were keen as lances in the sunlight, and yet profound, the wells of deep memory.
-- The Fellowship of the Ring, Book 2, chapter 7: The Mirror of Galadriel
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Quando ela chega para levar Frodo e Sam ao Espelho:
Even as he spoke, they saw, as if she came in answer to their words, the Lady Galadriel approaching. Tall and white and fair she walked beneath the trees. She spoke no word, but beckoned to them.
-- The Fellowship of the Ring, Book 2, chapter 7: The Mirror of Galadriel
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Quando a Irmandade a encontrar novamente para seu último adeus a ela e a Lothlórien:
In the midst of the vessel sat Celeborn, and behind him stood Galadriel, tall and white; a circlet of golden flowers was in her hair, andin her hand she held a harp, and she sang.
-- The Fellowship of the Ring, Book 2, chapter 8: Farewell to Lorien
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Quando ela chega a Minas Tirith após o fim da Guerra do Anel:
First rode Elrohir and Elladan with a banner of silver, and after them came the Lady Galadriel and Celeborn, Lord of Lothlorien, riding upon white steeds and with them many fair folk of their land, grey-cloaked with white gems in their hair; and last came Master Elrond, mighty among Elves and Men, bearing the sceptre of Annuminas, and beside him upon a grey palfrey rode Arwen his daughter, Evenstar of her people.
-- The Return of the King, book 6, chpater 5: The Steward and the King
(toda ênfase minha)
Então pode ser, como você diz, apenas Peter Jackson querendo mostrar os pés de Cate Blanchett. No entanto, como outros já disseram, ficar descalço se encaixa com sua imagem da deusa da natureza e com o que podemos supor do calçado de Legolas sobre a dureza dos pés dos elfos.