Again, targeting military forces on land requires intel that is near real time. Even more so when the accuracy of the systems is considered. Sinking ships bombing a known fort, no problem. Finding the military in a sea of civilians an impossibility at that time, and very time consuming today.
Mercy is ending the unrelenting suffering of war even when the means themselves are not merciful.
As an aside, my conscience is not bothered in least by any of this since I was not born yet.
What a surprise! Yet your stance never fails to denigrate the efforts of those who handed you your present.
There's no reason not to carpet bomb the fortifications ahead of time if you can. If you have air supremecy, you can carpet bomb at will. It's just not so glamorous to just walk up and find everything obliterated, as opposed to charging up at firing guns and half the guys getting killed. Always bomb the crap out of it first. Then, if there's anything left, go mop up. Better to have boring movies.
Your tactical acumen is breath-taking, where would these fleets of aircraft come from? How long between strikes? This plan of yours might take longer than your other stupid idea. Here the Japs are motivated because they can see and affect the members of the invading force. With your ridiculous bombing offensive Operation Milk Run there would only be the local morale boost.
Neither of the plans is decisive. Putting a force shore within range of enemy artillery that is bombed at best once a day, or sacrificing airmen while you search an area 3/4 the size of California at 200kts. There is always going to be 'something left' Douhet. What part of impervious to bomb and shell did you miss? Always! Every one of those positions would have to be rooted out, thousands of them. Hardly a 'boring movie'.