Actually one of the reasons they were murdered was because the Japanese high command didn't want to feed or transport the prisoners to Japan.
When the Japanese commander asked for transport and extra food for the prisoners he was told none would be forth coming and for him to remember the code of Bushido.
This code is the one that prevented any soldiers of the Japanese army from surrendering and it also considered any one who surrendered not worthy of life. In other words the high command was telling the commander on Wake to execute the prisoners.
These messages were decoded using the magic devices we had and the few Japanese codes we had broken. A matter of record.
The Average Japanese of WWII was utterly vicious and sadistic. The rape of Nanking and the general treatment of the Chinese, Philippine and other people who came under their control proves it.
Yes, that is true as far as it goes, however, one of those superior officers responsible for such orders was Terauchi, Field Marshal Count Terauchi, if I remember the name, rank, and spelling at the moment (forgive my error otherwise). He was in particular responsible for much of the atrocities committed throughout the vast regions under his command. He ordered the dismissal and sometimes disgrace of general officers who failed to carry out some of the war crimes he ordered. He was one of the officers the Emperor was most concerned about in addition to those in China when the safety of Allied POWs, neutrals, and civilians became a prime issue as the surrender developed.
A Japanese cargo or Hell ship was being used to transport some of the last walking and emaciated American POW survivors of the Cabanatuan POW camp to japan as slave laborers, when an American submarine sank the Japanese Hell ship. the torpedo tore a large hole in the side of the cargo ship. Some few of the nearly dead Americans were swept out of this hole alongside of the sinking ship. One of these survivors watched as the japanese lowered soldiers in a lifeboat equipped with a machinegun and manned by soldiers with rifles. They began gleefully shooting the American survivors in the water as their own cargo ship sank behind them. As the ship slipped beneath the surface of the sea, it created a large whirlpool and vortex of water into the dark depths of the sea. The lifeboat and the Japanese aboard it still shooting and slaughtering helpless Americans in the water continued even as the vortex sucked them underwater too.
The American submarine surfaced and rescued the survivor who witnessed these events.
An uncle who served two tours of duty in Japan told the story of a Japanese manager who befriended him. This man was a high school student when the atomic bombs took place. He told my uncle those bombs saved his life, because his school class had been assigned to attack the American troops on the beachhead with sharpened bamboo sticks.