They like the entire ensemble to be coordinated and look good.  Shoes can go a long way toward setting the mood and the theme for a look.  Low heels and flats may be businesslike and professional; athletic shoes may be for comfort or fitness, and high heels can make almost any outfit sexy, both from the look and from the way they change the posture, walk and body language.  From jeans to miniskirts, formals to funerals, nothing can say "sexy" and get most men's attention faster than heels.