Iga and his team aren't developing the Wii U and Vita versions, they are being outsourced entirely to Armature.
Iga even said he wouldn't let the Wii U port compromise the PS4, XB1, and PC versions of the game, and since Armature is handling the Vita version as well, the scope of the main development platform likely has not changed, with Iga and his staff handling the main version and Armature handling the other versions..
To quote verbatim ~
https://www.kickstarter.com/projects/iga/bloodstained-ritual-of-the-night/posts/1243827
With that in mind, a lot of you have asked about portsnot just because you want them, but because you want to make sure that making them won't affect IGA's vision for the game. We have good news, and really good news.
The good news is, it won't: IGA and Inti Creates are going to continue developing the game as before, without compromise.
The really good news is how they're going to ensure it won't: At our next stretch goal Armature Studio will join the fray to handle the Wii U version.
I don't know what else to say or what could be done to appease you.