Yes, the United States of America Should have bombed the United States because they soon realised that the Japanese would never surrender until something happened to the citizens. Once the USA bombed Hiroshima it instantly killed 80.000 people and killed much more throughout the course of 48 hours and even after years because of radiation. If the USA didn't drop the bomb no one would ever know if the Japanese could have even risked more lives then what had already been taken. Once the US realised again that when the Japanese surrendered there were no more deaths. If they didn't drop the bomb the Japanese would have kept doing kamikaze pilots and also could have risked more lives then what the bomb had done to Hiroshima. So dropping the bomb was necessary and it saved much more lives then if they didn't drop the bomb.
No, the US should not have bombed Hiroshima. The attack on civilians is a war crime, regardless of any military threat. The military take losses and make losses, it's their job. Innocent civilians should not have their lives and families taken away from them, or brutally disfigured when they most likely do not want to be in a war in the first place. Including both the Hiroshima and Nagasaki bombings, over 246,000 people were killed (that's just killed, not including all of the disfigurations and long term illness cause by the radiation). To put this into context, the U.S only lost roughly 418,600 troops during the entirity of World War 2. The bombings alone killed almost half the amount of Japanese innocents than Japan killed trained American soldiers. Similar war crimes committed by other countries are shunned by the U.S nowadays.