Shigeru Miyamoto illustrates the Wii Fit system, a new interactive physical fitness device from Nintendo.Credit...Michael Nagle for The New York Times IT’S O.K. to liken Shigeru Miyamoto to Walt Disney. When Disney died in 1966, Mr. Miyamoto was a 14-year-old schoolteacher’s son living near Kyoto, Japan’s ancient capital. An aspiring cartoonist, he adored the classic Disney characters. When he was