Consider how many people were dying EVERY DAY during World War 2. Sure, they may have been able to industrialize, but the world was in the midst of experiencing death on a scale we can't even really imagine today. The pressure to end the war must have been enormous. Which isn't to say that it was an easy, or even correct, decision, but we can't really do a simple calculation of "well they could have waited a few more weeks/months" and get a feel for the gravity of the situation.