I mention this because of articles like this one at Foreign Policy magazine, in which the author starts by claiming he frequently re-visits Hiroshima. He claims that the memorial has a clear meaning, a message, that he takes back from the site. It doesn't.
The museum puts the bombing into context. It shows how Japan had been in a constant state of war since the 1890s, with militaristic roots going back further in to Samurai culture. It showed how Japan would probably have continued their militaristic ways had the United States not demanded complete surrender, a near abdication of the emperor, and imposed a pacifist constitution on the country.
In other words, Japan accepts partial responsibility for having been bombed.
It doesn't shy away from the horror of the bomb. It makes it clear that such bombs should never again be used on humans. But even that has complexity. More people were killed in the Tokyo firebombing than Hiroshima and Nagasaki combined. Had Hiroshima not been nuked, it would've instead been flattened with conventional bombs, causing more devastation and killing nearly as many people. The Japanese were likely more afraid of the Russian invasion than American nukes when they surrendered unconditionally.
When I left the memorial, I was left with the profound sense that I just didn't know the answers.
The truth is that few have "real" opinions about the Hiroshima atomic blast. Their opinions just proxies for how they feel about American's military might today. The Foreign Policy article above, which claims to have gotten the "message" from the memorial, is a lie. Nobody gets clarity and focus on the issue coming from the memorial, just a new appreciation of the problem.