Morality depends on what you do to people, not the weapons you use. There is nothing mystical about nukes, they are just one more weapon. Firebombing killed more people in Tokyo and in several German cities than the A-Bombs. For that matter, Pol Pot's Khmer Rouge in Cambodia battered or stabbed more people to death with sticks and bayonets.
If nukes were just about numbers...then they wouldn't really add up much. You can talk about the destruction of downtown Hiroshima or Nagasaki...but people survived that were within 3 miles of the blast zone. And there are lots of city residents still alive today even though they did get a fair dose of radiation. There is a serious disconnect here by the media and some historians. Nukes do have terrible destruction power...but dropping 300 bombs over the area of New York City would just about destroy the entire downtown area...and probably kill over 150,000 people. It is the ultimate plan or desired goal of the destruction that matters.
One of the great destruction efforts of all time...is Kaiserslautern, Germany. In the 1300s, there were around 2,000 residents in the valley considered Kaiserslautern today. You can draw a circle of approximately 5 miles, and these 2,000 locals existed as mostly farmers. Hungarian raiders came into the area, and over a one-year period...between their destruction and killing...barely 400 people remained. It would take over one hundred years for the area to recover and reach its 2,000 population. If the raiders had never come...the population today (around 100,000), would likely be around 200,000. The destruction power of these raiders reset history for this community and can be gauged as the same force or power you might use in a nuke or a 100-bomber effort over a city. Its the death factor that matters, and not the method that was used.