I'm afraid I can't quite understand what your points there are, robomatic, but I think you misunderstand what I was trying to say. I'm not primarily talking about the actual decision-making process involved in the bombing, and the subjective morality of those involved, but about the ethical judgement we make about what was done, which affects how we judge other things which haven't happened yet.

And my point was that only if we follow a rigorous utilitarian logic, that sees any action as justified if it's good consequences outweigh its bad consequences, can we see Hiroshima as justifiable - and that this kind of logic lands us in some very strange company. There is an alternative view, that there are some actions which can never be justified. In theory that is the the one which underlies the concept of war crimes.
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It occurred to me that perhaps an expression that sums up the whole controversy about Hiroshima is "Needs must when the devil drives."