Dunno, maybe Scoob and some others can comment on this one, but if I were to bring up a few humble assumptions, I'd say because it's a new next-gen system with amazing Japanese support [sometime in the future anyway], FFXI, all those great [Western aimed] RPGs and because everyone should be first in line to get one in fear it'll be sold for weeks....
On a more serious note, Microsoft's unfortunate software delays is one thing, on the other hand, it's not really as if the Japanese have no idea about the software that going to come its way. I'm sure sales will pick up from here, but don't expect any miracles either.
True, but dedicated longterm support* isn't going to be something easy if they fail to make a larger impact in the market those dev-houses primarely cater to. That also includes valuable Square-Enix support and others.
*dedicated longterm support not as in ported-software, but exclusive support with larger developer teams etc.