In addition, women, knowing they present an erotic picture, array themselves with more confidence and grace. The required walking pattern changes, because she must take a more mincing step. The heels themselves can be viewed as phallic symbols, the inner part of the fronts symbols of penetrative entry.
Mules suggest the slapping associated with spanking.
It has been said that a woman's body in spikes emulates her posture during orgasm. I don't know how true that is, but I can see from where to idea came. The air up there is not so thin, but rather imbued with the delights of knowing that all those below you envy you.