they are releasing it first on USA cause of metroid......japan can NEVER get metroid first,it is a rule,and since it is coming with the console(even though it is a demo)....
Actualy, I bet its because of Christmas. Nintendo thinks that instead of a early 05 release, releasing right before christmas will bring a huge raise in sales on this side of the Pacific. Probably, the only real reason for not releasing in Japan simotaniously, if not earlier, is the fact that Japan doesn't have the same shopping rise and they only have a production line large enough to handle 1 major market's sales. Just speculation, but I bet they finished far before they expected to and figured they would hit the big US shopping dates.
PS. I'm not 100% sure about Japan not having the sales raise. I mean, I don't know that much about their culture, but I believe I'm right. If not, tell me. I'll admit te wrong and apologize if so.