Feet have multiple curves which is generally aesthetically pleasing to look at it, especially the female feet which are small, cute and hairless in contrast to large, hairy men's feet. The feet also produce pheromones, so even smelly feet, can be a turn on for men finding the odour arousing. The fetish thing- some believe it's to do with neurons cross wiring because the parts of the brain responsible for the genitals and feet are located next to each other.
