In The House on Mango Street, why do the girls get tired of being beautiful so quickly?

In The House on Mango Street, Lucy, Rachel, and Esperanza are gifted three pairs of high-heeled shoes by the mother of the little foot family. At first, they marvel over how long and lean their legs look, and how different it is than their normal look. They feel beautiful, because they think they look more grown-up and glamorous. The novelty of this new experience wears off, however, when they wear the shoes out of the house and walk down to the corner. When they reach the corner store, the owner Mr. Benny tells them that the shoes are dangerous and that they better take them off. This frightens them and they run away. After that, they run into a boy on a bike who hollers at them, confusing them. Finally, a bum on the street tells Rachel that she looks pretty and offers her a dollar to kiss him. This frightens Lucy, who grabs her hand and the girls run all the way back to Mango Street and hide the shoes in a bag under the back porch. Because of the unwanted attention from multiple boys and men that they've recieved, they no longer wish to feel beautiful. They decide that it might not be worth it after all.