Why do people second guess the killing of Osama?

they wanted him to be taken alive ,where he could stand trial for the 9-11 event.and he was the mastermind behind the plot,and the loss of billions of dollars (in 2001 dollars just think it he ordered it today ,then it would be trillions ).i really don't remember if there was a daycare center there ,but we do know there was one in Oklahoma city,he earned it(the right to be killed ) .