Plato's Theory of Forms states:
The only true being is founded upon the forms, the eternal, unchangeable, perfect types, of which particular objects of sense are imperfect copies.
In this sense, Daisy is Gatsby's Platonism, his other-worldly dream. He wanted to recreate the past by having her admit to Tom that she never loved him. Her voice was the sound of money. She is symbolic of Gatsby's love affair with the American Dream, through which he reinvented himself and went from rags to riches.
Nick, in particular, admires Gatsby's Platonic ideals. Gatsby is "better than the whole damn bunch" of the hypocritical East Coast old rich. Nick identifies with his cousin too; that's why the date in chapter 5 is arranged at his bungalow. He sees his own idealism acted out.
Gatsby is a novel of contradictions. Gatsby's idealism makes him blind. He doesn't see that Daisy can't have love and money, just money. Gatsby can't turn back time. He doesn't see death coming. He can't reconcile reality and idealism, and neither can Nick. Daisy is a temptress, a symbol, not even a real character. Her voice is full of money, but she doesn't really say anything.
Fitzgerald seems to be saying that America looks ideal from a distance, but if you look closely, it's a facade.
I don't have one, but would like to thank you for this insight, because I couldn't come up with any. I recently went back to school after 5 years, so I'm in the process of learning by asking questions.