Probably because they didn't have the wealth of historical info then that we have six decades after the war. For instance you already know that the Japanese have sonar. The US Navy wasn't certain they did before the war. Hearing Japanese destroyers pinging came as a shock to most US skippers. You know where Japanese ships are likely to go. The real wartime commanders could only guess and subs were sent to sulk off harbours that the Japanese had already left. Pre war training wasn't as strigent and intense as in the German Navy which had already fought a submarine war and was staffed with men with that vital wartime experience. Plus, the harsh reality having the lives of several dozen men on the line became as a staggering mental blow that resulted in some skippers being relieved. And real submarines come with a huge host of bewildering problems...mechanical, navigational, personnel, lack of spares and enviromental... that the game doesn't completely simulate.
