The office requires that the president play many roles, wear many hats. He must be accessible to the public and to members of Congress; he must conduct affairs with foreign governments and foreign dignitaries; he may need to make public appearances and keep up certain traditions.
Wartime, or any time when American soldiers are in battle and experiencing many casualties, constrains a president’s behavior somewhat. His commander-in-chief role becomes more prominent. Some of the light-hearted presidential perquisites must be put aside. This is not difficult to understand.