Like someone else said if the sconsole was selling well no one would be saying the name is at fault. The Wii U problem was and still is lack of software, lack of marketing, NEGATIVE stigma surrounding the console, and Nintendo kind of out of touch approach to gaming itself. I remember when the Wii was a crappy name and would be the console downfall. it didnt happen because they had good marketing, great games at launch for the system, and a positive stugma surrounding the console.
The problem with the wii u name and the wii name are complete different.
When the wii came out, bad or not, the name was unique, their was no other product, nintendo or otherwise, that shared the name or similar features, or even design.
THen the wii u comes out, The console looks practically indistinguishable at casual glance, can work with the same wiimote controllers, with practically the same exact name, no number after it, instead a letter 'U? What does that mean? must be that tablet thing, I already have tablets, I dont need one for my wii anyways'.
It was a horrible horrible name and message, and a major factor in a lot of the problems you brought up.