I could be wrong but I believe that the greatest thing about Iwata's leadership is that Nintendo has been able to identify problems and react to them before they happen.
The Nintendo DS was spawned in reaction to news that Sony was developing the PSP and releasing it 18 months before Nintendo was scheduled to release a successor to the Gameboy Advance; knowing that this was the exact same position that allowed Sony to take over the home console market with the Playstation (and to continue their dominance with the PS2) Nintendo produced a console to compete directly against the PSP. I suspect that much of the DS' design was influenced by the need to be different enough from the Gameboy Advance in order to claim that this was not a proper successor to the GBA.
I expect that Nintendo realized that High Definition was not going to motivate the average consumer to spend an unusual ammount of money to buy a gaming console, and that the development cost on Higher Definition games was going to prevent Nintendo from being as experimental with their game design. From this I believe that they designed the Wii from the need to encourage people to buy a system which was not centered around graphics.
