Development cost is a huge issue as well, for all small - medium Japanese developers.
Aside for JRPGs a lot of Japan games have no audience at all outside of Japan, so they have to be cheap to make and profitable at low numbers (50-100K). Put that same game on PS3 and it'd need to clear 100-200K sales at least, which for those games would be very difficult, especially with a low install base.
As for JRPGs themselves, the same applies but with higher sales potential & requirements. As of today, if I was a Japanese developer I'd make games for the DS and PS2 which have the large install base and low development cost, and maybe a PS2 port to Wii - which is getting there but small-mid developer Wii games have sold like total crap so far in Japan.
Until PS3 has at least a 5 m base, I don't think it's worth the risk to pay to make a game on it unless your SE or have a strong proven IP.







