Remember that the Pearl Harbor attack was a failure on Japan’s part. Their goal wasn’t to sink a bunch of battleships, but to sink America’s aircraft carriers…and all the carriers were at sea. Sinking carriers would have bottled the US Navy up in the eastern Pacific, allowing Japan to do as they wanted in the western Pacific. They wanted the US to be powerless, not especially to draw them into a war. By the end of the war the Japanese really wanted a decisive battleship engagement to prove the superiority of their ships (they had the two largest battleships in the world), they started off knowing carriers were the key to all their plans.