Bethesda: Wii U is "not on our radar". "It's largely a hardware thing."

[Locknuts]

The engines they use are not supported by Wii U. Therefore their games won't work on the hardware 'as is'. It would take work. Work that they obviously don't have the time, resources or drive to put in. I would totally buy The Evil Within on Wii U though. Love Mikami's work.