The wii is a lot more complex to construct than your average PS3 or 360, what with motion sensitivity. I think that 1.8 million is enough to supply demand without the factories overproducing the wii, causing the technology to not work with maximum efficiency.
I don't know much about the topic though, but I'm sure quality control must come into it somewhere.
Correct me if I'm wrong on this statement, because I'm not sure if I'm right or not.







