thats still 50mil people who could have gotten the game. I think it would have been around 15%

See now we're on the same wavelength. I completely agree with the bolded.

Oh please, no. This is the last thing they should do. Nintendo needs to offer a game experience that is different from their competitors. I welcome new IPs or reboots but the day they start to mimick other 1st party studios and look for what is trending at the moment -like any other 3rd party company-  is the day they really have no more reason to exist as a console maker.

They tried that with Wii U, it doesn't work. Mainstream gamers don't want "different". If they did, Wii U's sales wouldn't be so dismal.

Of course you can't just make something unconvetional and hope for it to succeed. Offering something different means, looking at the market and evalute if there's an hidden or unserved demand by competitors. You'll need to look at the market in a diffrernt way and serve it in a different way. They did so when they developed Wii and DS, and also when they developed the Gameboy in the first place. How much is the WiiU really "different"? its pretty much a standard console with a screen attached to it, you leave it (and use the pro controller) and you have a regular console.

Also, I was specifically referring to games, 1st party games will always remain their main differentiating factor from Sony and MS, you leave that and you are left with an empty shell. The fact Nintendo makes "Nintendo games" and not "mainstream mature games" is the only reason why the 3DS still managed to sell 60m units instead of 10 like PsVita and with a clearly inferior hardware.

Xenoblade X is first party. Just so you know. 

Nobody says they have to stop making games like Splatoon and Mario Kart, but these games alone cannot carry a console to mainstream success in today's market. An lineup composed almost entirely of E-rated cartoon games doesn't cut it in 2015.

It's unfortunate that these type of games are not as appealing as they used to be, at least in the Western part of the world. Sure, they have their audience and those who are more open-minded about the look of the games they played will be able to see and appreciate what these games represent. However, we're now in a time where technology has grown and the majority of consumers expect something else. Having games like Metroid, F-Zero, Fatal Frame, Xenoblade, Bayonetta, etc., will at least show that Nintendo is expanding their library, in terms of diversity. With Splatoon, Fire Emblem, Kid Icarus Uprising, and Xenoblade Chronicles X emerging as key games this generation (for both 3DS and Wii U), it will be interesting to see where Nintendo goes from here.

I undersrtand what you mean, I'm all in for variety but "hardcore" games like Xenoblade or Metroid (unfortunately) will never move a huge amount of consoles for Nintendo; their purpose is to serve top users and generate goodwill from the media - but those top users have likely bought the 3DS or the WiiU anyway. It's not really a matter of M-rated VS E-rated games, its more a matter of consistency between the target, the console's market offering and the content.

To make an example, take New Super Mario Bros Wii vs New Super Mario Bros U

The Wii's market offering can be summarized as: local multplayer that is affordable and for everyone.

Nintendo knew that, in fact they have turned an historically single player game into 4-player platform/party game. It was an instant success, beacuse for the market it was clear what the Wii was offering and NSMBU perfectly realized that promise: in fact it was a local multiplayer, that everyone was familiar with and could easily understand and it was also affordable (in bundle with the console).

Now firstly the WiiU's market offering can't be easily determined (and that is probably its main problem) but it's clearly different form the Wii. Since the gamepad is its main innovation it's hard to say the console is designed for local multiplayer (you can only use one). Is it affordable? no, it still costs more than Wii on day one. Is it for everyone? Hardly since the main goal of the gamepad is to add depht and that is not an easy concept to understand.

New Super Mario Bros U is exactly the same game as its predecessor: it perfectly includes the values of Wii but completely uncoherent to what the WiiU was offering. Of course a user who bought the WiiU on day one was expecting a game to utilize the controller in a meaningfull way and was also expecting a graphical improvement, since he had paid more for the better hardware. So this explains why NSMBU underperformed.

You could do the same "exercise" with Metroid Prime to tell why the 1st entry in the series sold more on 20m userbase than the 3rd entry on a 5 five times larger one.

A game like UC/TLoU would push more units only if Nintendo designed a console aimed the same target and with the same features as Ps4/XB One but at the same time, a console like that would weaken the potential of many core IPs like Mario, Mario Kart, Pokemon, etc.

That's the thing though, the audience who buy games like Uncharted are the majority now, hence why PS4 is doing so well by catering primarily to this demographic.

The market for a console geared primarily for the likes of Mario is shrinking, hence Wii U's poor sales.