I don't think that would have made the movie better, it would have made it align better with your view on the events. Honestly I would enjoy a movie made under your views better, but for what the film was only showing him was best. This might sound stupid, but the problem with the film is ultimately the society which created it. They do show his arrogance, but because of how great man theory works in westoid culture, this is just a quirk or slight failing. We feel bad for him once he feels guilt, even though we should feel revulsion at his actions, due to the fact we always treat what he did as justified.

I also disagree with the moment of the bomb dropping as the key moment of horror. Far more people died from the US fire bombing campaign than either bomb, the destruction of families was neither peculiar to the atomic bomb nor really a result of oppenheimer's actions in particular. The frame to show is the fallout. Fire bombs leave charred remains, atomic bombs leave a crater. And the poison it spread into the people who survived, radiation poisoning and cancer and the horror of seeing your loved ones made into shadows, that's what the bomb leaves behind. And that's what oppenheimer didn't prevent. It's not just a bigger bomb he made, and that's what the story should emphasize. He didn't know what it would do to people, but he never checked.