This is absolutely not what happens in the gaming industry. What would you say about the PS1? When Sony was focusing on creating a Mascot akin to Mario? Why was their direction geared to Crash but their classics ended up being Final Fantasy and Metal Gear? With the Wii, Nintendo released two killer apps during launch, Wii sports, and The legend of Zelda: Twilight Princess. How come everyone "suddenly" started flocking towards Wii Sports but willfully forgetting about the other behemoth in the room? Numbers also supports my claim, in the first year Wii saw a number of "mature" themed titles selling above a million, including third parties, while casual games were sent by the droves only to be flops one after the other with very few exceptions. The fact that third parties saw the Wii as a cash cow and not a viable system has very little to do with Wii sports, and everything to do with Third Parties' approach to the system. MS also grabbed support from Japanese developers, fostering an RPG environment with Blue Dragon, Lost odyssey, and gaining support from Square Enix with FFXIII, how well did that turn out?
My point is, Developers have had chances to create their own market within the console space (see WRPGS on PS3), and they do just that on every system released so far. What Nintendo has a problem with is the relationship with said developers, not the market. They don't listen to their needs for a console, they don't even acknowledge their existence unless it is convenient for them. The result is obvious, exploit whatever they can from Nintendo platforms as lazily as possible while putting their best efforts else where. It has very little to do with Mario or Zelda or Metroid, after all Pokemon didn't suddenly turn the handheld market into a local multiplayer competitive platform, even if it's one of the best selling titles 3 generations in a row now.
That's where creating new IPs come in handy,
It doesn't matter that Twilight Princess is technically a mature, AAA game. It was from a longstanding Nintendo franchise. That game selling only PROVES that people buy Nintendo consoles for Nintendo franchises. Want to send the message to developers that there's an audience for a certain type of experience on your hardware, and not just specific franchises? You do it with new IP.
Funny thing is Nintendo KNOWS that. That's why they created the Wii_________ line of games to sell the sell the Wii's features, and didn't just slap on Mario like they always do.