Those slides are trying to offer some future guidance coming out of the huge declines from prior gen. It's a forward looking document, and is basically saying that the consumer spend the market enjoyed during the Wii era has left the dedicated console market.
These slides are actually communicating what you are wishing it did, it's just doing so in a different way. Instead of saying "the Wii was huge and it declined and now the market is down and those people left" it's saying "removing the Wii, we see that the other platforms are stable/have grown". The end result is the same thing. "The Wii was this powerhouse console that provided a ton of consumer spend that is gone now. So, pubs & devs, what should you focus on now?"
You're looking for long-term trends, and trying to parse whatever you can from the data available. The inclusion of the Wii data into these trends makes the data less useful. No one is discounting the Wii. It was just so successful that it doesn't align with any other set of data points. And, when analyzing real data, sometimes things aren't perfect. You have to take what you have, mold it as well as you can, note that the sample size is small, ensure that you communicate that the range of error on whatever findings are made is higher because of it, but you still need to come up with ideas of what has happened and why and what should be done about it. As an analyst, that's your job. You don't need to fight for the honor of the Nintendo Wii, there's not one person working in the videogame industry that is unaware of its importance.
You are completely, utterly, fantastically, amazingly missing the point of the data presented.
That would be great and all, however, when looking though most of the slides when dealing with dedicated gaming systems they actually include both the Wii U and 3DS figures in several of the revenue slides and software releases slides for "gen 8" slides. And in all honesty, I still wouldn't infer anything from just long term sales data with out looking at macro-factors. When publishers flooded the music market with crap ton of guitar hero and rock star games middle of generation 7, what set in? People got tired of it keeping up with all of the releases and stopped buying it.