From: St.Petersburg, Russia
For one, they held very different tactical doctrines with regard to TF ship deployment. The IJN favored maneuverability over close in AA support. Probably because they feared torpedoes above all else. Pretty logical when you consider their torps worked rather well. Yet this tactical doctrine was at the detriment to DB attacks where concentrating heavy AA around the high value unit was the best way of disrupting the DB's performance. Given the poor quality of USN torpedoes it is clear that the IJN would have been better off adopting the USN CVTF deployment doctrine.
A very belated answer, I know, but I have to say this is incorrect. Japanese tried to use tight TF orders for AA protection early in the war, abandoned them, as it seems, after the Battle of Coral Sea, because AA guns on their escorting ships were too few in numbers to make much of a differense, and returned to them in 1944.
Also, tight TF orders were primarily useful against low-level attacks, considering practical realities of Japanese anti-aircraft armament throughout 1942 (no real DP guns on destroyers, existing DP guns lacking ballistics to effectively engage divebombers), so a loose formation was the most effective countermeasure to divebombers Japanese had until late 1944.