The way the economy is
The rise of the yen (which ironicly is not good for the japanese market)
The fall of the pound/euro (either one) which forced nintendo to increase the price to keep profit up
The US dollar pretty weak still (though i dont know how low it is)
Mr. Iwata said it himself a few months ago about its not allways a good business move to drop the consoles price inorder to gain demand and profi, esp when the economy is in bad shape.
One thing i am certain FOR SURE is that soon nintendo will bring the players choice line to the wii and DS and bundle some games for both.