They already had the example of what happened on Saipan, when Japanese civilians - sometimes entire families - threw themselves off of cliffs because Japanese propaganda convinced them that they would be horribly mistreated by U.S. forces.
Okinawa had a fair amount of that sort of thing, as well as massive civilian casualties.
Anyone decrying the use of the 2 A-bombs is merely displaying their ignorance of the history of the Pacific War. Those bombs saved millions of Japanese lives.