This has nothing to do with queues. It has to do with the fact that there's no reason for NA to have so few shards. JP has a heck of a lot more shards and the same size player base.
Its squeenix. Thats how they do. JP could have half the active playerbase of NA instead of less than half the total playerbase, but 90% of the active playerbase of NA, it wouldnt matter.