His faults....
1. He expected war in March 1942. He based his defense plan on this. The schedule of arrival of materials for him to carry out that plan was predicated on this. The Japanese decided the war would start in December 1941. He did not then modify his defense plan to take what the enemy was doing into account. Among the failures was failure to ensure as part of his administrative duties that sufficient supplies were on hand to withstand a siege that his Plan B (War Plan Orange, defend Bataan and the Forts for 6 months to buy time for relief) was in place. Hundreds of thousands of tons of food were left in supply dumps all over Luzon and not moved. This cost many lives as weakened men caught diseases they could otherwise have fought off and then ultimately died either in Bataan, or from the Bataan Death March or from their imprisonment because they went into captivity far weaker than they should have been.
It also resulted in the troops being so weakened from hunger that when the Japanese launched their final attack that broke the line, troops were so weak from hunger that many simply could not respond. MacArthur is responsible for that one, not the US government.
2. He refused to recommend awards for units of the Navy and Marine Corps even though as theater commander it was his job, assuming (at best) that it was the job of the Navy (that was his actual excuse).
3. He visited Bataan exactly once as theater commander and only went to Mariveles. His personal courage is not in question, but his judgement as this earned him the name "Dugout Doug" by the troops in Bataan most certainly is
4. His decision that resulted in the Air Force not launching an immediate attack on Formosa was based on the stated desire for the Japanese to make the first overt act. He stated this after being informed of Pearl Harbor which was an act that literally could not have been more overt. Now you can argue that the Far East Air Force and its mere 35 B17s was unlikely to do much actual damage, still he didn't know that. So again, his judgement is in question for failing to see Pearl Harbor as an overt act.
5. There is strong evidence that he took a very large payment from President Quezon, as did some of his senior staff. While not illegal, certainly you can call this questionably ethical and most definitely you can question how appropriate this is. Certainly my Great Uncle in the 200th Coast Artillery didn't get any money from President Quezon, but he did starve at Bataan and spend his remaining 8 years after captivity in a VA Hospital due to being hopelessly crippled.
6. His deep criticism of Wainwright at the time of the surrender showed a marked failure to understand the strain his troops and commanders were under. This was certainly due to his being out of touch with their actual condition.
7. Buna... he failed to ensure that his troops had proper support and make the necessary effort to overcome logistical and transportation issues that would have done so. The Australians managed to get field artillery and tanks in small numbers to the battle. There is no reason American troops couldn't have been given the same support. This cost American casualties directly and indirectly, as American troops were fighting a fortified position with grenades and rifles, and indirectly as it lengthened the battle and thus increased the time the troops, already suffering a near catastrophic illness rate, were exposed to those rather appalling conditions. He again failed to visit the scene to see what was going on himself.
8. Rabual.... he was insisting on a direct assault until the Joint Chiefs said no. Only then did he decide to by pass it. Rabaul had 100,000 Japanese troops at this point in strong fortifications. It would have been at best a costly Okinawa type battle, while at worst a costly Allied repulse
9. Insisting on invading Leyte to build airfields to support the drive on Luzon. As it turns out Leyte topographically was unsuitable for airfield construction. His failure was to insist on getting sufficient intelligence to determine if it was actually a place that a useful base could be constructed. There were guerillas in the area, it was possible to get experts in to check, and for that matter there were old maps and studies available. His failure is thus again deciding that his judgement and decision was not subject to other factors.. in this case... nature.
10. His insistence in sending an entire field army (the 8th) to liberate the southern islands which could have been bypassed easily, where guerillas controlled most of the countryside, and Japanese units were in static positions and lacked the ability to move out of them. This cost American and Filipino lives .. lots of them, while having no effect on the course of the war.
11. His insistence, even when overwhelming intelligence information was pouring in that the Japanese had massively reinforced and fortified Kyushu that Olympic was not going to be unduly costly. Luckily for everyone, including him, this turned out not to matter.
12. His insistence that American and ROK forces push to the Yalu River in spite of Chinese warnings via India that they would act, followed by consistent and determined efforts to ignore the presence of very large numbers of Chinese troops in spite of frequent clashes with them, some of which resulted in entire ROK battalions and regiments being wiped out, and then, when it could be ignored no more, not stepping in to reduce the route of the 8th Army in the western half of Korea that resulted in unnecessary losses, and his continued demand to use nuclear weapons and bring in KMT forces when told to shut up and soldier.
So yes, in my mind, his failings in terms of his behavior and judgement and that this failings cost directly and indirectly American and Allied lives in large numbers makes him overrated.
While his treatment of Australian and New Zealand commanders and troops was cavalier at best, that was a relative minor failing compared to the above
but would like to hear any reasons why I should be ?