I wouldn't exactly say that we did very little to the majority of it's ground forces. The Japanese culture was imbued with the philosophy of death before surrender. This made them fierce in battle and yes, little was (or could be) accomplished in changing
that aspect among their ranks. Though fierce as the later battles proved, they also proved that despite altering their tactics away from the early Banzai charges, little could be done to change the casualty ratio between them and their U.S. counterparts. Even in the battle of Iwo Jima, a unique landscape with every possible advantage to the defenders and where U.S. casualties outnumbered the Japanese (casualty lists included number of wounded), the Japanese deaths were three times higher than the U.S..
Even Peleliu, American deaths were about 1,200 compared to about 10,000 for the Japanese. By the time Okinawa was over, these contrasts in numbers killed would grow even larger. About 12,500 (U.S.) to about 95,000 Japanese. In my opinion, we rendered their ground forces ineffective. This, by no means, trivializes American casualties or the sacrifices our armed services made. If the Kamikaze was self-evident of anything, it was proof of the desperate measures needed to offset the ineffectiveness of their naval and ground forces.
We destroyed their ability for troop deployments and resupply. During some of the battles, the Japanese reverted back to the useless Banzai charges with nothing more than spears or bayonets affixed to poles. These are not the actions of an effective fighting force. It was their mere Bushido Code that not only kept them fighting, despite the futility, but also caused the catastrophic differences in the actual number of those killed. Wounded would consequently not be a standard of their casualty lists.
Yes they had the men, but I don't believe they had the means. Our tradition of holding life sacred, which I believe is superlative, causes us to count the casualties (rightfully so), that much more valuable.
