We have a long thread about this, the most important part of a plane is it's pilot, planes can be replaced, experienced pilots cannot and the lack of protection gave the Japanese aircraft long range and good low speed agility but at the cost of everything that made a warplane a warplane. The IJN had some of the most skilled pilots in the air in 1942 but once that top tier was lost the quality was lost with it. As for the endurance, A6M pilots prefered the 20mm cannons and would land as soon as possible once it was expended, as mentioned it in Shattered Sword the carrier decks were kept clear so the CAP fighters could be re-armed as required so having the endurance to fly around and around watching surface ships fire in the direction of incoming attacks to then only have about 10 seconds worth of ammunition for your primary weapons once you engage is not really a war winning strategy. The A6M could have had pilot armor and armoured tanks, even alloy double skin armour like the RAF fighters to protect it's pilot while still having a performance advantage over the F4F.The greater endurance of the Zero was theoretically also a great advantage as it allowed greater flexibility in CAP operations. Again, this advantage was largely negated by the Japanese lack of fighter direction.