Berichter -- You asked:
Was the treatment of PoWs in the camps a deliberate government policy of neglect and abuse or was it the result of both Japanese mindset and a faulty Japanese logistics system?
In the case of the Bataan death march, it appears to have been the result of faulty logistical planning and an unwillingness to admit that fact. Instead of the subordinate officers going to General Homma and telling him: "We don't have the trucks or other transportation to move those prisoners according to schedule without having to beat, shoot and bayonet stragglers," the Japanese officers went directly to the beatings, shootings and bayonetings.
Later, the Japanese treatment of POWs was equally callous. I have not seen orders requiring Japanese troops to treat the POWs in an inhumane way. However, I have not seen many instances where a Japanese commissioned officer or non-commissioned officer was put on trial for inhumane treatment of POWs either, and there was no shortage of such treatment. The policy of the Japanese government toward the POWs was at best negligent, and their failure to properly supervise and punish abusive personnel amounted to a ratification of the inhumane treatment in their POW camps.
You also asked:
I'm trying to puzzle out why the Japanese PoW record during WWII had arose, since the Japanese were famous for their equitable treatment of Germans captured in China during WWI. Or was it simply that the Japanese mindset had changed since WWI?
I cannot reconcile the accounts of Japanese treatment of POWs in WWI with accounts from WWII. Something must have changed for the worse in the command, leadership and training of their soldiers to have produced the WWII results.
You can find links to accounts of POWs under Japanese rule at:
http://forum.axishistory.com/viewtopic.php?t=44352