Dropping the bombs was the right thing to do.
Yes, civilians were killed. These same civilians were being trained to defend the homeland against an American invasion. Caves on the islands were stocked with weapons. Men, women and children were being taught to fight with pitchforks, pointy sticks, knives and guns if they could get them. All in defense of an almost mystical homeland and a divine Emperor. So... while they weren't combatants yet, they would have been in an invasion.
On the other side we have just under a million troops... weary from fighting fanatical Japanese resistance throughout the Pacific and angry from what they discovered when they liberated the prison camps. You're going to send these men into the homeland of the enemy to be met on the beaches by children with pitchforks. Just to show you how violent the defense department thought this would be they had nearly 500,000 Purple Heart medals prepared in anticipation of the casualties in the invasion of Japan. We're still handing out those medals today in Iraq and Afghanistan. Medals that didn't need to be used because we dropped the A-bombs.
It's estimated that the U.S. alone would have suffered 1,200,000 casualties, with 267,000 fatalities during an invasion and occupation of Japan. That's not counting casualties and deaths suffered by the Japanese which undoubtedly would have been higher. So even if the Atomic bombs at Hiroshima and Nagasaki took 200,000 lives it was far, far less than would have been experienced had the U.S. invaded. Far less.