They released it in Japan to shut up the xbox fans who though it would make the console succesful! /s
Seriously, they released it there to have units available to Japanese Studios and make it seem relevant to them in some way, even if the population does not buy it much, the Japanese gaming companies are still very important to the industry (see the latest TGS as an example).
So they have to maintain at least an image of trying.
This is like adverstisement for very expensive cars that go on a billboard beside the highway, it will be seen by hundreds of thousands, but the message is only for a very small percentage of people who are very valuable customers.







