(Sorry to cut all the quoted text), Might I just quickly make the point that the United States are in fact somewhat larger than many of the countries out there?
That being said, I can understand why there's an "American fan" and not one for smaller countries. However, it seems to me that this wouldn't be for Americans, but rather for non-Americans who support America (as it has been receiving a lot of negative press and the world hates it, and so on).
Anyhow, userboxes are stupid, but I don't think this makes /Wikipedia/ biased or POV. It could easily be assumed that there is {{User America fan}} and no {{User Japan fan}} because none had been made yet.
But please don't make it. We have enough to delete as is.