I dont think it should be needed but it gives a better understanding when your deciding what to do during war time. You have been in the same situation as the soldiers you are in command of, and they will also respect you more. Notice how the soldiers like McCain a ton more then Obama, its not a coincidence because Obama never served.
These are the only past Presidents with no military experience
John Quincy Adams
Martin Van Buren
Some good ones, but a couple who were just horrible