You just stated my case right there for why the Wii U and PS3 is so comparable. The 360 had more content and a price that resonated well enough with customers based on what the system was offering; I find the controller arguement to be irrelevent for the most part because that is highly subjective and as I recall while Sixaxis lacked rumble some people were actually happier with its layout because it was similar to that of PS2. As for Wii U doing worst than PS3, I agree, but you also must consider that the Wii U has had far less content than PS3 did at this point and it pales in comparision in terms of things such as media content (again precieved value of content offered for price is lower for customers). Until Nintendo matches the price of the system to the content they are offering, I cannot see the Wii U gaining significant momentum.

Another thing to note with the Wii U and 3DS situation is that Nintendo believed they had become a premium brand (like Apple and somewhat like Sony) because of the success of Wii and DS, which is why they thought they could get a way with pricing the system higher; unfortunatly, what they did not realize was that they did not have the content nor the premium brand power (their brand has certainly been recognized but not as a premium consumer brand) to backup their product; thankfully, they acted early with 3DS but making similar adjustments to Wii U is going to be difficult at this point because they will most likely have to sell at a deeper loss than they ever did with 3DS.

motion controls were a bit of a fad and were sometimes used just for the sake of having motion controls and not to add to the game. There are so many good games on wii though, and motion controls were not the reason the majority of these games were good. Also, my grandma still to this day is involved in wii sports bowling league weekly.

Yes, it was.
It was the most brilliant console ever and it was even breaking records. Nintendo can be scary sometimes, the only company capable of creating fads worldwide.

X360 had little 1st party support from 2011 onward and costed more. Wii gone from out of stock to out of bussiness really fast.

It certainly was a "sprinter" by design, due to the low price and low performance compared to it's direct competitors, while HDTV adoption rates were already increasing quickly by 2006.

The problem I think is, that Nintendo let it run a year too long. In my opinion there still could have been some momentum to carry over to the Wii U if it released in 2011 (and with a tighter schedule for game releases).

Ofcourse by now we know that would have been impossible seeing how several of their studios still struggle with HD content creation, so I suppose Nintendo should have invested the Wii/DS money really quickly in many more additional studios to make sure they can push a home and a portable console to success at the same time.

They already achieved that with the Wii and the DS, but both didn't need much of a push - Wii was fine with Wii Sports and Wii Fit, while the DS went into overdrive after Brain Age and Nintendogs.

That is true, but a console like Xbox relies more on third-party support than Wii; and Xbox has had far more solid third-party relases than Wii has had in this period (or arguably ever in its life time); in comparison to MS, Nintendo consoles are largely dependent on first-party offering. A similar trend can be seen with DS, DS continued to sell well right until the end 2011 and even outselling 3DS at points in certain regions (even after the big 3DS price cut) largely because Nintendo was still supporting the system with games like Pokemon Black and White 2. In 2012, DS sales collapsed much like the Wii's sales collapsed because Nintendo dropped most first-party support. Similarly, speaking hypothetically of course, say if Nintendo dropped first-party support for 3DS this year, I would honestly expect the 3DS to crash (and I would expect a Wii like crash in US and Europe because these regions have very little in terms  of meaningful third-party support than a place like Japan).

I disagree with the Wii being a fad, but some are being way too defensive. In my opinion something being a fad isn't necessarily a bad thing. Fads usually do very well, it's in the definition. Something blows up and everyone gets it then once the novelty wears out people stop caring. So the argument that it sold really well so it can't be a fad is just wrong. Tamagochi for example is a huge fad and the thing sold like 80 million or something. Why I think consoles can't be judged whether they were fads or not is because it's typical that a console's sales drop after a while. Concepts can be judged however in my opinion.

First we need to define the word fad, as it clearly has different meaning to people.
But let us assume the word fad can be attributed to a product with huge short term sales, that suddenly drops to levels where its relevance is in question. Then I would say almost any game system can be called a fad.

On the other hand I have trouble attributing the term fad to any game system of relevance during the last 30 years. They are simply necessary parts of an evolutional chain. Atari 2600 to NES to Megadrive to SNES to Saturn to PS to N64 to Dreamcast to PlayStation 2 to GameCube to Xbox to Xbox 360 to Wii to PlayStation 3 to Wii U to PlayStation 4 to Xbox One...
One system being the result of all systems prior, and will continue being so as long as we have something called the video game industry.

Simply put it; Wii can not be defined as a fad.

I believe a more relevant question should be if motion control was a fad? I'd say that it probably had its peak with Wii and in some respect with Kinnect. However, motion control is here to stay, even though it probably won't be dominating the arena ever again. Instead I believe motion control will act as one regular way of playing video games along side other regular ways of playing videogames.

With that said, I do believe Nintendo failed in using the Wii Motion Plus to its fullest potential during the Wii era. This is clearly one of the reasons why Wii lost momentum in 2010 and 2011, because Nintendo in some ways abandoned their unique concept of easy game play. I'm quite certain that if Nintendo had marketed Wii Motion Plus more aggressive, dropped their old Wiimote early on and instead included Wii Motion Plus in all Wii packages, and shifted focus to developing more Wii Motion Plus compatible games, we would have seen sales of an additional 15-25 million Wii's.
On a more positive note though, the fact that Nintendo never used the full potential of Wii Motion Plus during the Wii era, points to lots of untapped potential for Wii U when it comes to motion control. That might actually be one of the reasons why Wii Motion Plus is included with every Wii U sold.

Lastly, the reason why Wii U is struggling in terms of sales has nothing to do with motion control being a fad. It's a much more complicated equation behind that. One such fact might actually be that Nintendo, not the market, has dropped motion controls in favor of the touch pad. There is a clear trend in Wii and Wii U sales; once Nintendo started shifting focus away from motion controls, they started losing sales momentum.

Pretty much what I'm trying to say, but written better. :p

Lack of NIntendo releasing software towards the end killed the system as dd lack of good 3rd party games (SO MUCH SHOVELWARE) and saturation of games like GH. Obivously we know why good 3rd party was missing due to spec differences but that is another story.

Also the support for the Motion contorller never really took off, alot of it was waggle controls. We saw glimpses of the potential if done right but sadly it was only a few games at best.