All well and good, but I still think there is a persistent tendency to underestimate the capabilities of the Japanese in WW2 even as we tend to exaggerate the capabilities of the Germans. And I think that may be in part down to who had the most effective propaganda.
I just listened to Part III of Dan Carlins "Supernova in the East" which just came out last week, and I was struck by the audacity and lethality of the Japanese war machine in late 1941 / early 42. Not only the attack on Pearl Harbor, but the seaborne invasion and conquest of Malaysia,
Java, and the Philippines, were carried out all more or less simultaneously (or in rapid and overlapping succession to be more precise), and for the most part flawlessly.
Malaysia included a fairly significant contested landing on a pretty well defended beach. The campaign in Malaya was conducted with a lot of improvisation (using fishing boats and bicycles to facilitate flanking and infiltration for example) skillful use of tanks, air support and naval assets, and was won against 2-1 odds - the Japanese had 70,000 troops and the British, Dutch etc. had 140,000. Philippines as I'd mentioned earlier was on a larger scale and also against a numerically stronger opponent (wikipedia says 129,000 Japanese troops vs. 151,000 Filipino and American)
All of this was also carried out at a time when successful amphibious assaults across such distances were fairly rare, and in which nobody had ever really even used aircraft carriers.
The
amphibious assault at Kota Baru - against a fortified landing site with barbed wire, mines, sighted in artillery and concrete pillboxes, was at a much smaller scale than say, D-Day or Galliopoli, but it was certainly hairy enough that it could have gone badly wrong and in it's successful execution, a pretty good training run for a larger scale operation in the future.
To ground this back into aircraft, I think the Japanese military aircraft in 1941 and early 1942 were extraordinarily capable. They may not have been as fast or high flying as the best German fighters but they proved superbly capable of shooting down Allied aircraft and sinking Allied ships, and quite effective at CAS as well. In my opinion the A6M was definitely not inferior to any other fighter in the world at that time. I'd put it in the top 3 fighters - the Spitfire, the 109 and the Zero.
In a theoretical attack on Hawaii, Japanese resources would not have been divided between four major campaigns. They would have been concentrated. Arguably the strongest, best trained and most capable naval war machine ever assembled in history.
As I said upthread - the major flaw in any theoeretical Japanese attack plan, the one which I do find convincing, would have been fuel and logistics. Especially fuel oil for ships. That is a big hurdle. If the fuel didn't exist for such an operation then it just wouldn't have happened.
The other two hurdles - the vast distances and the prepared defenses, while substantial, maybe aren't insurmountable. Prepared defenses availed nothing in Malaysia. Japanese troops were ideal for a task like storming beaches under fire. They would have formidable support in the form of naval artillery. Ok sure fine Yamato can't use it's big guns for bombardment I'll take your word for it, there are several other Japanese battleships available for that and to duel with the shore guns. The Japanese have the various Atolls and small islands I already mentioned - Midway, French Frigate Shoals, Johnston Atoll, they had 4-6 fleet carriers available and 4 or more light carriers too, plus maybe a dozen slower 'escort' carriers. They had those astonishingly long ranged bombers plus float plane fighters. Most of their aircraft have much longer effective range than most Allied equivalents. Long enough to help cope with Pacific distances. I can also imagine the Japanese capturing some of the other Hawaiian Islands to use as a staging area from which to attack Oahu. Lets remember, Hawaii is far away for the Americans too and IJN Submarines would be waiting between California and Hawaii as well.
Lets also remember that the Japanese proved quite good at pressing their warships into service as temporary troop transports and even supply ships. The Yamato was at one time loaded with two battalions of infantry. Cruisers and destroyers could carry more, some destroyers as we know were modified to be fast / armed transports for use in the Solomons. So this capability should also be kept in mind.
Putting something like that together would have been a
huge challenge requiring near genius level of organization, imagination, timing and resourcefulness. But the Japanese proved they were indeed capable of that between Dec 41 and April 42.
And as for the notion that their plans were too complex and inevitably fell apart upon contact with the enemy, I think that is the confidence of hindsight. Lets keep in mind that the US had partially broken the Japanese code. This allowed them to leverage their Strategic and Tactical responses to Japanese chess moves with ideal counters. Like having your carriers right where they need to be at just the right time. But the US didn't always have all the Japanese codes broken, the code breaking is in fact another semi-random element. If the Japanese codes are broken prior to a Hawaii assault, then yes once again I give it to the Americans. If not, I'm not so sure.