Why do the Japanese in the single-player campaign use Kamikazes even when they are winning and are about to take Hawaii? And why did they make land-based fighters and fighter prototypes carrier-borne when they could just as easily have modelled the A7M and had that as an upgrade instead? (Yes, yes, Rule of Cool and all that)
The aforementioned reasons are probably the penultimate ones, but I'll give it a whack anyway. The simple fact is that the Japanese Air Forces prior to the outbreak of open war were the cream of the cream, having been selected from the finest and brightest and then put through Training from Hell to refine them further, which paid off wonderfully (as we can see in Pearl Harbor, the raids on Singapore and Ceylon, and the attack on Henderson Field). However, by the time of Midway IOTL, those fine young men had had their ranks thinned massively, and Midway was a tipping point that forced Tokyo to skip the prior intense training and start putting them through basic training just enough to make them worth something before they were torn apart by the Corsairs, Spitfires, Mustangs, and other Western Allied fighters that were coming into maturity by that point in time. And while the Japanese victories in that campaign do remove two of the main motivations for that (1. Lack of resources, with the conquests either being liberated or simply getting cut off, and 2. Pressure from the advancing Western Allied fleets), one of the main issues remains: the experienced pilots. The battles they had to have fought must have done a number on them, and reinforcements will take longer to train, so Tokyo probably chooses to organize suicide squadrons manned by enthusiastic, young and inexperienced volunteers to save the experienced cadre that still remain and because the cost is far more marginal if they are simply shot down. And as for the Carrier-borne issue, Tokyo probably forsees an invasion of Australia and New Zealand followed by a campaign in the Indian ocean at least to Madagascar and some other islands on the Africa coast - and if that fails, another try in Alaska and perhaps even the Pacific coast of North America, and (in Australia particularly) carrier based craft would be a vast advantage, given the logistical issues of landing and the handful of suitable landing sites (which coincidentally happen to be amongst the most well defended). The Japanese really considered making more of their aircraft types carrier borne, but in this reality (with the Japanese victorious), they have the resources to actually do that.