It would also appear that Nintendo had a lot more to do with development of the game than just publishing it. It appears that the original concept was to be a medieval game, but Nintendo wanted it to be more unique. It also is evident that Nintendo approached Platinum to work together on their own new IP. With that in mind, this pretty much nixes the idea of a simple money hat.
I think this is a brilliant way to work with 3rd parties. They did not just buy an IP, they helped create one and was heavily involved in what the game came to be. This further justifies their ownership of it, and I could see them continuing to outsource their own ideas for their own IPs to 3rd parties to further strengthen 3rd party support for the console.
After all, who needs the games on every other device when you can just create new IPs through outsourcing to keep from you in jouse devs from being spread too thin?