User blog comment:Plexioth- xD/Monster Hunter 3 Ultimate/@comment-3298463-20111220214129/@comment-76.69.7.125-20111221025439

It's not like they ran out of the budget for importing the rest of the P3rd monsters. It's probable that they want to leave certain monsters exclusive to keep up the sales for older games. So 4th gen could end up with the same issue.