Dravenet7 on 19 January 2017
Basically it was near in the development for a while. Rather than resources up-porting a game (which fans would just complain it hurts the sales of the Switch) they could have used developing a brand new game in time for next year; they chose to just do what they did.
Also I don't really recall a single port from 3DS to Wii U but I can recall several the other way around off the top of my head. Down-porting is easier and cheaper than up-porting.
