There's a huge difference between "thinking" something and actively assigning resources to study it in depth. And I don't see anyone calling for prosecution in this entire thread. Criticizing, sure, but wouldn't you criticize me if I spent time and resources trying to figure out how to kill tons of people? And GP acknowledges the difference between studying what would happen if the dam failed and how to simply kill massive numbers of civilians. Our point is that you can't just say it's okay to kill 1M civilians because "war is hell", "war is hell" because of stuff like that.
And--perhaps ironically, from your point of view--the data and conclusions from the military study of the dam probably lends weight to the urgency of repairing it, thereby actually contributing to saving lives.
You've also neglected to consider that the dam could be attacked by anyone, including terrorists, competing regional forces, and (perhaps in Desert Storm) the Iraqis themselves. Imagine if Saddam Hussein had threatened to destroy the dam and kill millions of people unless the invading armies left.
Without knowing what would happen, it would not be possible to make a sound strategic decision, prepare for relief and evacuation, etc. It's better for everyone to know what would happen if the dam were attacked.
