This question is not easyily answered without deep research but in my opinion, its not about the Japanese. It's about cheap labour and its evolution from there. Same outlook can be said about why most things are made in China. Economics and the history of Japan are subject that might shed light on this matter.The reality is that the people there grow up learning to build circuits and electronic gadgets. Most importantly because of cheap labour the companies are able to increase in revenu. Some employees then begin making their own line of products.