The attack at Pearl was a RAID. As such it was best suited for the Mobile Striking Force (i.e. Kido Butai). The Japanese Naval command structure was devoted, to a degree that is nearly impossible to overstate, to the Concept of the Decisive Battle. The main battle fleet was to be preserved, at all costs, until that moment arrived. That battle was supposed to take place near Formosa, well inside land based air coverage and after the Kido Butai and submarine forces had reduced the American fleet (keep in mind that the U.S. was, based on 5:5:3, 40% larger than the IJN in the battleship category hence the decision to construct the ultimate manifestation of the super dreadnought). Everything prior to that battle was mere shaping of the battlefield.
Alright things are starting to become more clear. So the Kido Butai was not the main fleet, that would be a fleet with more battleships(Kido Butai had only 2), the "combined fleet". They saw the usefulness of flattops to raid, but not as part of a decisive battle. Of course, the Americans proved them wrong on that part.
Still, Midway was supposed to be the decisive battle right? They wanted it more close to their own lands, but their carriers gave the ability to fight it out over American territory(?). The Japanese hoped to lure the American fleet out from Pearl and meet their invasion force to defend Midway. At first i had thought they wanted to kill the American carriers with their own in a decisive battle, but there is actually a bigger picture wasn't there? the carrier battle was not the decisive battle they wanted. They used the 4 carriers to lure them, yet their destruction caused the cancellation of the battle the Japanese actually wanted, one that their first fleet and second fleet took part in, versus the American battleship fleet. But, by failing to surprise the Americans and get surprised and overwhelmed themselves they ironically gave the victory of the decisive battle to the Americans. I guess after Midway the Japanese were aware of the value of carriers though, but by then of course they had no hope of getting their numbers back. The Battle of Leyte gulf destroyed the image of the battleship permanently.
Am i warm?