I answer with the question, "What girl is not fascinated by a Cinderella story of any type? Most girls love the idea of a rags-to-riches transformation. If I were ever to play the part of Eliza, I would look to Hepburn's performance in George Cukor's 1964 My Fair Lady, based on George Bernard Shaw's 1913 Pygmalion, for inspiration and emulate her vernacular (as both a flower girl and a duchess), her actions (from coarse to graceful), her emotions (laughter to tears) and, most of all, her strength. Above all else, Eliza's character must be strong if she is to be a believable lower-class-turned-upper-class woman.
But perhaps my real reasons for wishing to take Hepburn's role as Eliza are really because of the elaborate costumes worn by her character in the musical. My favorite scene in the film takes place at the Ascot horse races, when all the characters have donned their finest clothing for the event. Everything Eliza wears following her transformation is gorgeous, from the jewelry to her elaborate dresses, down to the very last detail of her hats. As a fashion-conscious consumer, I find Eliza's clothing enchants me most of all because who would not mistake her for a princess wearing such an exquisite evening gown and jewels?
Perhaps Hepburn's performance can be viewed as an ice cream sundae, each part of her performance constituting a different flavor or topping. Her beautiful clothes are simply the cherry on top. Why do I want to play Eliza? What girl does not like ice cream?