I think it is much (much) simpler than that ...
Durring the Playstation/N64/Saturn generation most large third party publishers went through a 'growing up' phase where they replaced their existing executives with 'experienced' executives from the Television, Movie and Music industries. These new executives were able to market videogaming far more effectively towards the growing market of teen and young adult gamers by putting a focus onto the higher production values and more in-depth experience of videogames.
Many of the executives in many major publishers heavily discounted the Wii mainly because they had no understanding of why someone would buy a videogame with lower production values than another one that was available; this lack of understanding is similar to the moder focus of Hollywood on Special Effects and production values over acting, direction, plot, and characters. They see the Wii's success and are forced to respond and they mistake the success of games like Rayman Raving Rabbids to mean that Wii owners only want simple game experiences so that's what they provide.
We're begining to see the second stage now, where intelligent executives realize that one of the reasons Nintendo has been so successful with the Wii is that they have produced a wide array of games which appeal to the conventional gamer as well as the new 'Blue-Ocean' gamer; as a result you will see more companies react by producing more "Core" gamer games along side their "Blue-Ocean" games.
