Wow.... i can't imagine what if something like this will happen to Google or Facebook. If it happened to Yahoo, why not to them?
And to put this in context, IT in Japan is about a decade behind the West.
Sure, plenty of companies are behind. But quite a few are too in the US... http://www.pcworld.com/article/249951/if_it_aint_broke_dont_...
I'm also not sure that "new" means more secure in this kind of context either. LinkedIn ain't exactly ancient and had a similar breach last year.
[1] Anecdotal data etc etc.
While Y!J and Y!Inc are separate entities, the former does borrow/use technology from the former and some of the Y!J services use Y!Inc servers and/or services maintained by Y!Inc.
Y!J user ids are completely separate from Y!Inc though (Y!Inc ids are shared through out the Y! locales).
It's been almost a decade since I was at Y!J, but from what I understand Y!J does continue to leverage the Y!Inc relationship for services and servers.
Additionally, simply stating that old technology is the reason for a security breach could be a red herring, it isn't always the age of the technology but how it is implemented.