I know that it’s been adopted as a handy way to tell first names from surnames on business cards, especially if the businessman is Japanese and deals with English speakers. If a Japanese person puts his Anglicized name on a business card, he might occasionally move his family name to the right as a courtesy to his Western associate. This seems sensible, until you realize that there’s no firm convention for how this should be done anymore. Capitalization immediately removes all doubt:
GOTO Dengo
Ken WATANABE
Shigeru MIYAMOTO
Junichiro KOIZUMI
This way, when receiving a business card, the Westerner can take a quick glance, and immediately say “Ah, thank you, Goto-san. I hope we can work together for our mutual benefit.” …and he can be pretty sure that he has not just called the guy “Mr. Dave”.