The Japanese were ready to fight for the Emperor, to the last man, wave after wave of foreign troops on their soil. In order to end the war, it was right for us to bomb Hiroshima and Nagasaki. We had to demonstrate that we were more powerful than the Emperor by showing we could eliminate entire cities in Japan without having a single troop set foot on Japanese soil. We were right to do it.
Yes, the US was right to deny the emperor power as far as Hiroshima and Nagasaki, because that was an effective way to use military force. In a time of war political niceties need to be suspended. Acting in the best interests of Americans is far more important. The United States did the right thing and swiftly brought an end to the war.
The U.S. had to deny the emperor because the emperor was seeking to destroy us. Regardless of the reasons things got to the point they did, and one can debate for hours whether the U.S. might have been demonstrated a bit of excessive force on Hiroshima and Nagasaki, the fact of the matter is that we were in a position that our shores were threatened if we did not do something about it.
Imperial Japan was an outdated form of government that had no place in modern society. When the Japanese surrendered and the U.S. military occupied post-war Japan, one key change to be made was to make Japan more democratic instead of imperialistic. The emperor was all-powerful and needed to be replace lest Japan rise to power again in another decade.
Given that the Japanese planned and carried out a full on attack of the United States that killed many of our military personnel, it was the right thing to deny the Emperor power. Japan did what no other nation, country or entity had attempted to do, prior. Because of their ability to create technology and hoard power it is best that it is kept in check. Our decision to drop nuclear bombs was a bad decision, however.
I do not think that the bombing of HIroshima and Nagasaki were necessary. I know that they were bombed in order to stop the way and to potentially save the lives on countless American soldiers. But the price was many many many Japanese citizens, including women and children. Not only were people killed instantly, but thousands were killed in slow agonizing ways. The effects of the bomb are too numerous. I don't think it was worth that many innocent lives.
Although I can empathize with America's aim in bombing those locations, I believe that some form of diplomacy might have prevented the events from erupting in such a manner to begin with. We as a nation are extremely prideful to begin with and quick to jump to our guns and bombs if we perceive any sort of offense, big or small.