Balance, in general, is good. You probably often heard that too much or too little of anything is bad. Balance is the key. Moderation is another term. A balanced diet, a balanced life, lead to a balanced way of thinking.
Physically, you need it as well. You cannot always be on both feet. Sometimes situations may make you stand on just one. Have you tried standing on one foot then the lifted foot goes backward while your body and arms forward? How long do you think can you stay that way without tipping over? If not long, you need to develop your sense of equal proportion with a balance cushion and you can find yourself competing with others.