I have two reasons for wearing my watch on my dominant hand. First, my dad, who was a righty, put his watch on his left hand, and I just copied him. And second, I began wearing watches before batteries were common, so we had to wind them every night. Since the stem was always on the right side of the watch, it was easier to wear the watch on my left hand and wind it with my right hand (which faced the stem) than it was to wear it on my right hand and try to reach across and super-pronate my left hand (turn my hand so the back faces my right and the palm faces my left) to wind it with my left hand. There was a reason most lefties learned to do many things with their right hand--it often required a contortionist to use equipment designed for a righty with the left hand.
