The Nazi's were denied the oxygen of publicity as information about the concentration camps was sparse and understandably, many people simply didn't believe ordinary human beings could behave with such brutality and inhumanity. it could be argued that this gave them time to continue with the master plan of wiping out the Jews, the Roma gypsies, people with disabilities, and indeed, anyone who disagreed with them. Very like IS it seems to me.
The murder of another innocent Japanese hostage is unforgivable but I am relieved the Japanese government didn't pay the ransom. Starve IS of money, that'll slow them down a bit