Wii brand was already becoming passe and dated by 2011, by 2012 like most fads it collapsed hard.
Switch is an actual brand with a bedrock below it built on a solid foundation. Wii was always a fad type of thing, so it was basically a platform built on a bubble.
Once that bubble burst that whole thing collapsed. Not just Wii but Kinect also collapsed hard in the same period. When people get tired of a fad it collapses in sudden fashion, not gradually.
The pricing, marketing etc. wasn't the issue, it was that this bubble was going to pop eventually. You could call it Wii 2 or Wii Z or Wii Pee or whatever you want and make decent commercials for it, the crux of the concept -- another Wii console, was what was poison. People by 2012 had got tired of that whole style of gaming/console and moved on.
Most people realized that Brain Training didn't really make you smarter, and that Wii Fit for most fat people still left them fat, and Wii Sports was boring after the 1000th time and same with 18000 different shovelware mini-game titles. People just had their fill and the smartphone was a much sexier/cooler draw for the attention of that audience.