Where are you pulling this concept from that "the casuals didn't buy games?"
Of the top selling games of the 7th generation, the Wii had 5 out of the top 5 and 7 of the top 10. The PS4 didn't have a single game make the top 10.
The Wii had 8 games that had more than 4 million in sales. Comparatively the 360 had 5 such games and the PS3 had 4.
The Wii had
6 games that had more than 8 million in sales. The PS3 had
0 and the 360 had only 1 in Halo 3. And Halo barely made it with 8.1 million, Wii Fit sold over twice that.
The Wii might not have had as long of life compared to the 360 or PS4 (which who cares, it wasn't made to be a "10 year console"), but to say it didn't move software in its prime is completely false:
http://vgsales.wikia.com/wiki/Best_selling_games_(seventh_generation)
Of the top five selling games for the Wii (which again are the top five selling games for the whole generation), the top three had NOTHING to do with Mario and one of the fourth was only partially his game (Brawl). Only
one of the top 10 selling Wii games was a traditional Mario platformer.
Sure the third parties did not have a lot of sales on the Wii, but that is a different issue that honestly matters only to those companies and not to consumers. The key point is the Wii sold games and it wasn't just the bundled Wii Sports.
Breaking sales records because you are selling an almost generic x86 computer with less supply constraints than ever before (after a longer gap than ever for a new generation) isn't that impressive. We will see either the PS4 or the Xbone pass the 100 million units sold mark like the PS1, PS2 and Wii? I would bet not.
Meanwhile there are hundreds of millions of iOS and Android devices in the world, and some of those games have sold over 10 million copies:
http://www.gamespot.com/articles/minecraft-pocket-edition-sales-reach-10-million/1100-6407847/
Oh and competitors like Amazon's Fire TV are going after the casual gamer that the major consoles have left behind.
The only thing the current market shows is that many of the traditional game developers and much of the hardcore market have their heads stuck in the sand about the general direction of gaming's future.