The chapter on Wii U was a bit short, I think he was avoiding going into detail as to why it launched that way to avoid giving too much detail on a very recent event. No mention of fallout with EA , the hardware decisions, etc, but he addresses issues for the Wii U that he and Nintendo tried to fix for the Switch
The key focus was software, both first and 3rd party. He said Nintendo's secretive nature meant they preferred not using middleware and he had to push to change that with Switch by making it compatible with popular 3rd party development engines. And the proof is really in the pudding. He was right.
That said the chapter on the 3DS did reveal some insight as to decision making at Nintendo. There's a core executive management team consisting of Iwata/Genyo Takeda/Miyamoto/Kimishima (note how every single name is now semi-retired/retired or gone from NCL) and a CFO whose name I forgot that met regularly (like every two weeks) and Reggie felt was where all the decisions were made. This was the team that he noted aligned on the 3DS' $249 price point even though Reggie said he pushed hard for $199 for North America. Reggie did say he felt that team lacked insight on western markets So if we extrapolate that to the Wii U decision making you can see where thhey might have gone wrong.
Reggie did push hard to join that team to provide a western perspective, but was rebuffed. After Iwata's death Kimishima created a new larger team that included more outside voices and Reggie was the first person from America named to that grouping.
So when I say upthread that a lot of things have changed and there's been huge turnover at the leadership level, I am also referring to how decisions gets made. Because the decision making is very different post 3DS/WiiU , we shouldn't assume it will be more of the same. That said, they could make similar decisions, but given we have very light track record on their decision making so far, I am still taking a wait and see approach. It's a bit frustrating when people extrapolate what happened 20 years ago as relevant today. My guess is that it is a lot less relevant than we think.