I would wager it has partially to do with the different racial components of the two theaters, and the subsequent disparity in the "goodness" of the war in each.

The fight against the Nazis has been continuously held up since the 1940s as the epitome of a "good war." American soldiers fought and died to liberate Western Europe from a Fascist anti-democratic foe, which has been consistently depicted in propaganda and pop culture as evil incarnate (an example of the latter might be the frequency with which Nazi soldiers are the bad guys in FPS video games, whose deaths in the games are never controversial). The eugenicist and genocidal practices of the Nazis lend greater support to this idea of the European theater being a fight between the forces of good and evil (this is helped by the fact that American eugenicist and anti-Semitic policies in the 1930s and 1940s are largely unknown or under-known by Americans today).

Meanwhile, the American war in the Pacific is not nearly so easily depicted in stark moral terms. Although the war was initiated by a sneak attack carried out by Japan on the US, the American response to that attack was to corral the West coast's Japanese American population, citizens and noncitizens alike, into concentration camps. Furthermore, American propaganda throughout the war depicted the Japanese in explicitly racist terms; while the war in Europe was depicted as a fight between freedom and fascism, the war in the Pacific was depicted as a fight between white democracy and Oriental despotism. Finally, anti-Japanese sentiment lingered for decades after the war ended, while anti-German sentiment almost immediately disappeared at the beginning of the Cold War.

In short, it has been relatively easy to depict WWII in Europe in terms of stark moral and political contrast (good vs evil, democracy vs fascism, liberty vs tyranny), while America's war with Japan was much more controversial, both in terms of its conduct (concentration camps, racist propaganda) and its aftermath (lingering anti-Asian sentiments and violence). Given this state of affairs, pop culture more readily focuses on the European Theater while paying much less attention to the Pacific.

I agree with u/Darth_Picard. Nazi Germany is (today) a "safe" representational target in a way that Imperial Japan is not; both because of the relatively muddled morality of the Pacific Theater and the fact that, at least in recent decades, film studios are wary of depicting wholly non-white antagonists to mostly white protagonists, fearing any (usually justifiable) accusations of racism.

Another important element may be the tremendous influence of Jewish people – including European refugees and subsequently their children – on the American pop-cultural landscape, in particular Hollywood. The horrors of Nazi Germany naturally had a particular, personal resonance in their lives and the lives of their families, friends, and communities, in a way that stories of Japanese atrocities in East Asia did not; nor have there ever been many people of East Asian decent in Hollywood influential enough to decide the stories that get told and those that do not. Part of the impetus behind Schindler's List, to take just one example, was Steven Spielberg's own familial tragedies during the Holocaust. (Compare that to popular media in China, where movies and TV dramas about the Japanese occupation are ubiquitous.)

That said, although you [OP] are doubtless correct about the relatively low quantity of Pacific Theater movies, I might rebut that nevertheless some of the finest war films are set there. Consider (and see if you haven't already) The Thin Red Line, The Bridge on the River Kwai, Flags of Our Fathers / Letters from Iwo Jima, and Empire of the Sun (which despite what I said earlier is of course also a Spielberg film).

In addition, if you're interested in the Pacific War generally, you do yourself a disservice by not watching Japanese films on the subject – and there are a lot. The best (by far) is The Human Condition, parts I-III. I'd also recommend The Burmese Harp, Fires on the Plain, and Merry Christmas, Mr. Lawrence.