Perhaps Paul chose the feet, hands, ears, and eyes as examples because of their prominence in the body. Even though they are prominent and important they cannot stand alone. They need each other. [source][source][source]
". . . Chrysostom remarks that the foot contrasts itself with the hand rather than with the ear, because we do not envy those who are very much higher than ourselves so much as those who have got a little above us ..." [1][source]