Regarding the Japanese development culture, I'd say they fell almost immediately into what's now the dominant world-wide usage model for computers: they're scary boxes that you use strictly according to the manufacturer's directions.
In the West that didn't happen until Windows 95 hit (the final demise of the Apple II in '93 and the C64/Amiga in '94 probably also played into that timing). Prior to that you basically *had* to be a hobbyist to get anything to run on a PC.
In all cases, the same thing results: without a hobbyist culture there are no serious demo or emu scenes, and as the hobbyists get older there's no new generation picking things up.
