Board Thread:Theories and Speculation/@comment-26005711-20150719134117/@comment-1512913-20150719140125

Because it's not anyone's business to mess with life and death. Death is natural, if everyone were revived, there would be no point of dying. The only reason Nagato used it is because those people died by his hands, Sasuke was on the side of the alliance in the war, he didn't kill them.