The movie was about the man, not the bomb, which is why it focused primarily on a man, and not a bomb. The actual testing of the bomb was a small part of the movie and the real deployments of it were but a couple sentences. The movie Oppenheimer was never a movie about Hiroshima and while I think there needs to be more coverage in general about our impact on Japan by dropping those bombs, I think giving the movie Oppenheimer shit about it isn't reasonable just because the man worked on it. It covered everything from the his view point, and what he personally lived. He read about the bombs being used the same as everyone else, and it wouldn't have fit the movie to suddenly jump to Japan to show the impact of his work. It did however try to visualize the impact and eventual realization of what he had played a part in, in the visuals at the compound when he's giving the speech to the fanatical coworkers stomping their feet (which was very Aronofsky like imo)