This may not be necessary, but I just want to again go on record as saying that I don't see the need to view this as a referendum against Mario. The numbers on the 3DS may not match the soaring highs of the Wii or DS, but they are still solid. I really don't see why anyone would view this as anything but a referendum against the Wii U.
Ignoring my joke post earlier, perception and brand association of a platform is very important in my eyes. Rather than having one or two big gaming franchises, it's more important that your brand has a strong association with diversity, industry support, and is the general home to many big franchises. Nintendo's biggest problem with home consoles is that they have increasingly been isolated since Playstation entered the scene, and the Wii did nothing to help them in the long-term regardless of how successful it was initially. They created a system in the Wii U which is, essentially, shit. It has no real redeeming qualities and Nintendo have not done a good job of making their brand very appealing to the general gaming audience. Part of that was born from necessity due to the Wii taking a diverging path and Nintendo trying something very different after N64 and Gamecube did poorly, but the biggest failing with Wii U was that Nintendo didn't leverage the success of the Wii to try and make an entry back towards the traditional gamer with a more powerful platform and more aggressive approach to securing third party support. They also timed their launch wrong as the industry moved with Sony and Microsoft.
It's a stark contrast to their handheld, which whilst still finding it a little difficult outside of Japan, has a much stronger brand and quality in the eyes of general people. That's thanks to the established precendent of success and quality leading all the way back to the Gameboy. It's consistency.
Nintendo home consoles haven't been consistent, and the company in general seems confused.
@Verendus: The PS2 days for Sony are long dead. Sony is still very much in crisis mode, no matter how much the PS4 appeals to you.
They've been out of crisis mode for while. The PS2 days may be long dead, but the Playstation brand is more than healthy and poised to be the industry leader once more. If $599, a late launch to market, a terrible production template, and a mass exodus of exclusive support didn't manage to do much more than slow Sony's mindshare down, then there isn't much stopping them now with everything going the oppositive way in terms of pricing, launch and future support from the industry at large. At least they've managed to sustain and protect the brand to set up future prospects, rather than flail around like Nintendo is doing with the Wii U.
But I'm sure your genius idea of focusing on the casual market and that audience is the right way to go for Nintendo in a post iPhone and tablet gaming world.