That is a good idea about limiting the Japanese Kamikaze use until they are kind of pounded down to a low income. The Kamikaze was a weapon born out of desperation after all.
Yes, and in addition to the pressure of Japan being in such a desperate situation, there was another related factor at play: the more the war progressed, the fewer top-notch pilots Japan had at its disposal. Japan’s training philosophy prior to the war had produced an elite corps of pilots, which gave Japan an initial advantage but left it in a worsening position as the years went by and their casualties mounted. The US Navy, by contrast, figured out that training large numbers of competent pilots was a better investment than training a small number of superb ones (especially since the US could produce enough aircraft to take advantage of its abundant pilot supply). When Japan’s situation became dire enough in late 1944 for it to consider extraordinary measures such as kamikaze tactics, one element which worked in favour of the kamizaze concept was that it required very little pilot training: the pilots basically just had to learn how to take off, how to fly to their targets and how to go into a steep dive. This kind of rudimentary flight instruction was the opposite of the elite-oriented training philosophy Japan had followed prior to the war, so it would make sense to have a rule saying that Japan can only make kamikaze attacks late in the game once Japan is on the ropes. Maybe this could even be seen as a kind of tech – a capability which isn’t available at the start of the game, but which becomes available later when certain conditions are met. With a normal tech, you need to invest money to gain the new capability; in this case, kamikaze attacks (a kind of reverse tech because it reflects a training downdgrade) would become available when Japan’s economic and strategic situation drops below a certain threshold.