Sympathy? ... Sure, but it was still idiocy. The Japanese send their best minds to be killed at the front long before the war was hopelessly lost. Even when the Russians stood at the gates of Berlin the Germans didn't send their scientists and engineers to fight (though some of them did so voluntarily).
Again, I must emphasize the difference of culture. Living longer than three thousands of years with people of same ethnicity at the same areas of the world is bound to have some effect on the mindset of many people - notably of the tree North-Eastern Asian countries of China, Korea, and Japan. Ofcourse, things have changed during the past few decades and the speed of globalization has 'softened up' the edges quite a bit, but still there are certain types of thinking that just doesn't go away.
Ofcourse a certain civilian section will probably be maintained to ensure the war machine keeps on going, but what if the tide of the battle has been turned decisively, and such efforts will not be able to stop imminent defeat? Naturally, everyone, every human resource will be put into the defense of the homeland, in whatever way they can. It's how people are brought up around these parts - it's just different.
It may seem hard to understand, most probably awkward, perhaps even 'idiotic' as you might say, but not our eyes who live here in Eastern end of the Asian continent. Ofcourse things have changed a lot since last 60 years, and if modern day warfare ever breaks out things would be a lot different. However, in regards to the Japanese of 1945, I don't find it too difficult to understand what they felt and how they felt it.
P.S. The AH Ki84 maxes out at about 384, NOT 398.
You're right. WW's test results are;
Speed on deck, no WEP: 327 mph
Speed on deck with WEP: 348 mph
Speed at 22,500 ft without WEP: 382 mph
Speed at 22,500 ft with WEP: 388 mph
Must have confused 398 with 388.