MacArthur responded to this by promising that he would return to the Philippines to liberate them. Thereafter, he insisted on a Pacific strategy that was in radical opposition with the official war plans, but which would honor this promise. The official war plans proposed a simple westward drive to Japan from Hawaii across the Central Pacific. MacArthur's plan took a round-about route northwest from Australia and New Guinea to the Philippines, north to Formosa and finally northeast to Japan. As Australia was further from Hawaii than Japan was, this would involve a very long supply line, running past territory still held by Japan, and thus easily attacked.
This did not seem to make much sense: but, in fairness, his strategy has some good points. MacArthur could argue that the supply lines to Australia had to be kept open in any event, unless the Allies were ready to abandon Australia to the Japanese. Further, the most important Japanese supply line was the one which ran from the Indonesian oil fields to Japan through the Philippines. This would be cut by his offensive, but not by the drive directly to Japan. Finally, the Navy plan required a huge fleet of aircraft carriers to overcome the powerful Japanese bases on the few islands to be found on the Central Pacific route, and this fleet would take years to build and train. MacArthur's route had thousands of islands that could be used for bases. The Japanese could not defend all of them. The Allies could land on any undefended island, turn it into a mighty airbase, and use the planes based there to support the next landing.
But the final argument ignored the fact that Allied over-all strategy said there would be NO offensive in the Pacific until Germany had been beaten. Thus, the time needed to build and train a huge fleet for the Navy plan was no problem; the needed ships would be brought from the Atlantic when the war in Europe was over.
It would have been logical to have ignored MacArthur, but it was politically impossible to repudiate his promise to the people of the Philippines, or abandon Australia. After the decision was made to send him a force to defend Australia, there was nothing to keep him from using it to "defensively" push the Japanese out of New Guinea (just like NIMITZ was then "defensively" occupying Guadalcanal). And once he had regained his reputation as a fighting general by saving New Guinea (and won the support of the Australian government) it was impossible to prevent him from continuing with his plan.
This led to more difficulties. Not only had MacArthur ignored his superiors and followed his own strategy, he had become an assistant in Australian Prime Minister Curtin's plan to take Australia out of the British Empire, which certainly didn't make Churchill happy! Later, his political activities went beyond grand-standing to get more resources for his command, when his staff advertised him as would-be candidate in the 1944 Presidential election! Although this attempt failed - the Democrats chose to run FDR again, in spite of ill-health, and the Republicans tried New York Governor Thomas Dewey -- MacArthur's behavior made him a political liability second only to PATTON.