Let's say Japan is irrelevant (which if obviously isn't), how does that change the fact it has spiked up in the US (where other bundles [including your own city and state] are obtainable)?

And checking retailers in my region reveals avaible bundles in various forms from various retailers.  Unless Franklin, TN doesn't have many Walmarts (20 according to Walmart.com), or Gamestops (25 or so according to Gamestop.com), 5 Best Buys, 12 Targets....and so on, I doubt MK8 is the ONLY means of acquiring a Wii U. 

To say nothing ot any of their online stores plus Amazon (damn near the largest restailer in the world).

You have to side step it like a tourist and assume it's a standard custom.