Actually it is like we don't have very many real world setups. The battles of Midway, Coral Sea and Guadalcanal can only be revised and rerun so much. Mention the Battle of the Solomons and IJ players chant "Turkey Shoot" (which is what it was). Pearl Harbor and Doolittle's Raid never were practical given the impossibility of actually achieving complete surprise on the enemy. And by the time the invasion of Japan rolls around, the Japanese were really on the ropes when it comes to putting up any sort of significant air forces (though we usually fudge that to balance things). A dynamic campaign where each setup can affect the next at least changes things up some. But then .... that's CAP.