To be clear: The film does not miss out Hiroshima and Nagasaki. This film does not overlook the horror and indeed the horrifying legacy of that bombing. But it tells the story from Oppenheimer’s perspective (with accompanying nightmarish visions as his overwhelming sense of guilt begins to close in on him). It’s a brilliant artistic choice that honours what happened to the Japanese without suddenly cutting to a scene in Japan (as none of the rest of the film is told there). Cutting to Japan at that point would have compromised the artistic integrity of the film and come off as tokenism (and that really would have been disrespectful).

I hope that clarifies. :)