I may be completely wrong about this, but from a British perspective it has always struck me as slightly surprising that for every 100 times the war with Hitler is referred to by U.S. Freepers, in all sorts of contexts, the war with Japan is barely mentioned once - even though, and forgive the grotesquely crude over-simplification, the European war was ‘our’ war, whereas the Pacific war was ‘your’ war.
My suggested explanation is not meant to imply that it's the definitive one by any means; I was born well after WW2 and so I would never consider myself any sort of an authority on the subject. However, one possible explanation may be that articles at Free Republic are usually threads commenting on published news articles, as is this one. Therefore, the numerical sampling will be skewed, to a large degree, based upon what's published in newspapers. Sadly, most "journalists" seem to be eager to minimize the profound suffering caused by Imperial Japan because these "journalists" are typically Leftists who are of the opinion that our nuking of Japan was a horrible war crime and should never have been done. Usually, articles pertaining to Japan's involvement in WW2 fixate almost exclusively upon the atomic bombing and the American internment camps and only give a passing glance, if that much, toward Japan's innumerable sins. This is in keeping with the Left's desire to denigrate the USA at every opportunity, and a newspaper article accurately documenting Japan's evils would be counterproductive to the "journalists' " anti-American agenda. There's an endless flood of articles about Japan /.Hiroshima, and I think that most FReepers tend to just roll their eyes and move on to an article that's not merely written as another tired America-bashing exercise.
Most FReepers don't like anti-American articles and so they typically won't post them, except in cases where the article and the writer are being mocked.
Although that sort of sentiment also exists in regard to America's involvement in the European theater (the bombing of Dresden is incessantly harped on by the Left) it seems to be of a lesser degree, possibly because the Left has managed to portray the Nazis as "right wingers" in the modern sense / parlance and so they eagerly write about that as much as they can.
Just one possible reason among many.