The man who bombed Hiroshima believes what he did was great and noble because, by killing 160,000 innocent people, he forced the Japanese to surrender early thereby preventing a long, drawn-out war as seen in Germany. He claims it's okay to kill innocent people if more lives are saved.
I suppose that means I am allowed to kill that man and then, using his blood and organs, donate them to several sick kids. He wouldn't mind that.
If what he says it correct then it's okay for me to go around killing innocent people on the streets so I can harvest their organs and give these organs to sick people.
This is illegal in most countries because it goes against individual rights. An individual's right to his own life is more important that the interests of "society." Ironic then that the Hiroshima bomber fought for America, the land of the free, whose constitution claims that all men are endowed with rights for "life, liberty, and the pursuit of happiness."