I'm someone who's been debating on whether the atomic bombings of Japan were justified. Before I go further, my main questions are basically as follows:
-In Operation Downfall, the invasion of Japan, why was there seemingly no consideration of bombing areas that were a target of the invasion, which would have drastically cut down on Allied casualties and made an invasion much easier?
-Why was a full-scale invasion seemingly the main option? What was the exact goal of an invasion if Japan's fighting ability revolved around the decisions of their government? Wouldn't smaller forces with more immediate goals been preferable, such as targeting the Emperor and high command? What were Operation Downfall's goals, and how would it have made Japan surrender?
-Why weren't the Emperor and High Command targeted for bombing?
I don't want to get too heavily into the morality of the bombings, but one thing I've come to find really strange is the overall strategy and mindset behind Operation Downfall, in that, with a full-scale invasion, the allies were expected to suffer mass casualties due to just how many Japanese civilians would resist.
At the same time- and I say this purely from a practical perspective in regards to the invasion- if we were to invade Japan and expected massive Japanese casualties, why didn't we mass-bomb atleast the areas (preferably with fire bombs) we intended to invade before we engaged in any sort of landing? This wouldn't solve the problem of potentially greater Japanese casualties, but it would drastically cut down on American/Allied ones. What I've read about Operation Downfall, the amount of troops devoted to the invasion, and the projected casualties, it seems to have been planned with minimal bombing (whether aerial or naval) of the target areas. Operation Coronet, which involved a landing at Tokyo, was set to occur over half a year after when we originally nuked Japan. The main landing areas for Operation Downfall all seemed like they were meant for areas bound to be extensively defended. In reality, I think we were capable of potentially wiping out most of Japan's population through conventional bombing (especially firebombing.) We had been bombing mainland Japan since April 1942, and before we nuked Hiroshima and Nagasaki, we had killed hundreds of thousands of Japanese through bombing. In contrast, we lost under 3,000 airmen. Our firebombing of Tokyo, which killed atleast close to 100,000 Japanese, left us with under 250 casualties. Japan's aerial defenses by the later stages of the war were pitiful. For this, there was ultimately nothing stopping us from wiping out most of Japan through conventional bombing, either predominantly or entirely, and getting them to capitulate even without nukes. There was nothing really stopping us from destroying even just Hiroshima and Nagasaki through firebombing. And we probably could have completely destroyed Tokyo months beforehand if we wanted to.
On top of all of this, I do not really understand why a full-scale invasion, with or without bombardment of the target areas and more, was the ultimate plan. Why weren't smaller-scale landing forces or strike forces planned instead? Since Japan's fighting spirit revolved around the will of the Emperor and their high command, wouldn't a plan that mainly targeted them, possibly through killing or capturing them, have been preferable to a full-scale landing force? Or, why couldn't we have targeted them alone through bombing? A full invasion really seems excessive in any regard. And for that, I don't understand the ultimate aims of Operation Downfall. What was our main goal with a full-scale invasion? Was it just to target the Emperor and the high command or more?
You are operating under a flawed assumption. That both aerial and Naval bombardment would remain static or slack in the lead up to November.
It was planned to do the opposite. With additional B-29's arriving in theater, as well as bases being completed in newly taken locations such as the Philippines and Volcanic islands, the offensive would be better supported than ever.
Meanwhile Naval bombardment was planned to continue. The fast carrier task force repeatedly launched strikes on the mainland in the summer targeting targets of opportunity such as trains or supply dumps. Indeed even the battleships got into the action with the British Pacific Fleet involved here.
The invasion of Kyushu was also not meant to take the whole island. The plan was going to stop about 2/3 up the island. Just far enough for good ports and airfields to be secure. Then invade the Tokyo plain once the weather calmed only if surrender had not come. While other ideas such as a fake/feint invasion first were suggested. The goal being to draw out the reserve suicide forces to be destroyed by a prepared and ready USN.
There was also real opposition to the scheme, the Navy in particular favored continued blockade and bombardments alone. Admiral King with the concurrence of Nimitz could possibly have created and unprecedented rift on the high command had his concerns about the optimism if MacArthur grown to great. The old War Plan Orange had never included invasion and they were content to a degree with starving Japan out.
As to your specific question about usage of the atomic bomb they very much did plan on using it in tactical support. On Restricteddata's great blog is the transcript of a conversation between an officer from the project and the planning office. The subject was using the VERY limited number of bombs(maybe 12 all told) the best way. The thought was that if the "other usage" of population bombing hadn't worked by August it was best to save them and use some in direct support too. With a bomb on a headquarters or gathering area about 2-3 days before the arrival if US troops seen as ideal.
And for the Emperor the palace was specifically off limits. The real concern was that without him or a large part of the Imperial family there would be no functional single group to surrender and thus it would get even uglier.
The US had diplomatic obligations and a domestic political imperative or total war to unconditional surrender.
The US was in competition for influence over Asia with the Soviets, and needed boots on the ground to win it. Indeed, as it turned out, everywhere the Allies got boots on the ground was saved from Communism and most of the places it didn't fell to Communism.
Bombing was not especially effective at degrading the enemy's ability to wage defensive war, especially a defensive war or insurgency on its home territory.