These guys are glorified when they shouldn't be. They all made incredible mistakes and cost more lives than they saved. Their men meant little to them and they saw them as the means to their glory.
Patton hated enlisted men and thought he was superior to them. He treated them horribly and moved them from battle to battle without rest. He would stop alongside the roadway and yell at his men for ridiculous uniform violations even though the men had just ended a battle and were walking to the next one without any rest.
McArthur had 9 hours to prepare for a Japanese attack but still, somehow, he did nothing despite numerous attempts by other officers who wanted to attack nearby Japanese bases. McArthur allowed his aircraft to be destroyed on the ground. He also received $500,000 from the Philippines President and then abandoned 50,000 to 80,000 US and Philippines troops who had to surrender to the Japanese and then end up in the Bataan Death March. How do you surrender 60,000 troops? That's an army. After WW2 McArthur also did not give any tanks or artillery to South Korea which likely caused the Korean War because the North knew they had the advantage.
Eisenhower chose to invade Normandy, where the Germans had significant defenses, instead of Brittany where there were NO defenses whatsoever. He did this because he was in a hurry. Invading Calais was impossible but Normandy was a bit easier, so, his thinking was that he was doing the troops a favor.
Bradley is known as the soldiers general but Bradley was in charge of the D-Day landings at Omaha Beach. While the invasion was ongoing Bradley knew that Omaha Beach was a slaughter and he knew that other beaches were completely open yet he still sent landing craft to Omaha. Two to five thousand troops died on Omaha, many of them could have walked ashore easily at the other beaches.
Halsey sailed his fleet into typhoons, twice. Two destroyers were sunk with all hands lost. When he was assigned to escort and support the invasion of Leyte Gulf he took off in pursuit of a fake Japanese message.
Just after D-Day the US troops got stuck fighting through the hedgrows in France. The Army generals got the idea to bomb the entire area with B-17's. The Army generals told the Army Air Corp general to bring the bombers in and drop the bombs going from the South to North. The Air Corp general disobeyed that order and told his bombers to drop from West to East. He thought they were so accurate that they could do it without hitting the US positions. They dropped their bombers on US positions and killed around 200 US soldiers.
Another US Army General prevented the M4 Sherman tank from getting a bigger gun even though tank crews were complaining that the 75mm was not powerful enough against the newer German tanks. The British had already increased the guns on their M4's to 17 pounders. He interfered because he wanted an entirely new tank with a better gun but it wasn't produced in time for the war. This guy cost a lot of tank crews their lives.
The only reason the Soviets and Americans won WW2 was because of homeland weapons production and the individual soldiers, not because any of these generals made good decisions.
McArthur was a dick sure. But what he did is not unlike other supposedly "great" generals in history. Like Napoleon leaving Egypt or, much later, leaving Moscow while his troops rotted behind. He saw the writing in the wall so he left to save his own hide. In the Napoleon leaving Egypt's case troop evacuation was really hard if not impossible because the British Navy controlled the seas in that area. It was one thing to evacuate a small retinue quite another to evacuate the entire army. The situation might have been similar in McArthur's case. Still, it is quite shitty to leave your soldiers in the dark while you make a clean escape.
I disagree with your evaluation on Eisenhower's idea to invade in Normandy. Have you ever looked at the coast of Brittany? The coast has steep cliffs and the seas have strong currents. Good luck doing an amphibious assault there. It is also further away from the British coast and was closer to the location of the German U-boat bases in France.
With regards to the M4 Sherman there were several reasons why the gun did not have a caliber increase. The USA had its dedicated tank destroyer corps and the US Cavalry doctrine at the time was that enemy tanks were to be engaged with tank destroyers while tanks were supposed to support infantry. The US Army had vehicles like the M18 Hellcat and the M36 tank destroyer. The M36 had a 90mm gun.