I definitely agree, an argument can be made for either side.
Those who were in favor of dropping the bomb took into consideration the difficulty in capturing islands like Iwo Jima and recapturing the Philippines. An invasion of Japan would have been very bloody and the loss of life on both sides would have been heavy. Plus the war would be extended. By calling for an unconditional surrender, we had backed Japan into a corner and they would fight to the death rather than be dishonored.
The result of the dropping the bomb has been a healthy respect for the bomb throughout the world.
Of course, humanity cries out against the action which was perpetrated on a civilian population. The target was not an army camp but a city filled with men, women, and children.
During wartime, leaders are often asked to make difficult decisions. For example, Churchill could not warn the city of Coventry of a massive German air strike without giving away the fact that they had broken the Enigma code.
War is indeed hell.
You might not receive a definitive answer to such a question. Be ready to see all sides brought out with this one. I do think that a case can be made to suggest that the United States was justified in dropping the bomb on Japan if they operated under the assumption that the Japanese army was at full strength and capable of anything. There was a contingent of individuals in the position of military and political power who did believe this. The notion of a "kamikaze" fighter and with the memory of Pearl Harbor still fresh in the mind, these individuals were convinced that the dropping of the atomic bomb represented the best chance to subdue the Japanese army and save the lives of America servicemen and servicewomen. There is another school of thought that argues that the Japanese were not as significant a threat with the European theatre closed. This line of logic suggests that within a few months, the Japanese Army would have surrendered, and seeking to end the fighting even before August's dropping of the atomic bombs. In the end, individuals have to assess both arguments for themselves and determine what they think is the correct course of action for the United States to have taken.