Basically for all the reasons everyone mentioned prior to me. It was almost destined to fail

Games: The Switch has far more intriguing games coming out in the first year than the Wii U ever did in its entire lifespan. 

Zelda BOTW, MK8D, ARMS, Mario Odyssey (much more hype than 3D World), Xenoblade 2, Monster Hunter XX, FE Warriors, Splatoon 2, and whatever they decide to reveal at E3, but we know that there's going to be a new No More Heroes, Project Octopath Traveler, SMT 5, whatever Retro Studios is working on, the new Pokemon, Pikmin 4, all somewhere in a timeframe of 2 years. 

That's better than what the Wii U could ever achieve. If they port Mario Maker, Smash, and bring the Bayonetta series to this next console, there's going to be almost no reason to own a Wii U anymore. 

Marketing: The Switch has had stellar marketing, at least in the states. Wii U marketing was non-existent.

Dev kits: The Switch dev kit is $450-$500. The Wii U devkit was about 5 times more expensive than that.

Underpowered: The Switch, for a handheld, it's impressive they could fit that much horsepower in it. So technically, it's not underpowered for its concept. It's not possible for it to be as powerful as the PS4. Unless they waited for Pascal, and opted for a higher price, but...

Expensive: Yes, they're both expensive. Switch is sold at around $50 profit so no surprise. I'll give it that.

Poor online services: Both fail in this area at the moment but I'd wait to see if Nintendo revamps their services when they actually start charging for online on the Switch. So there's still "hope" that they can change.

32GB storage: The Switch uses cartridges, slight advantage. But yeah, you probably will need a supplement microSD as not everything will get a physical release.

The only similarities in disadvantages are the online service, price, and storage. But the online services and price can be rectified in the future. There was a source where Nintendo said if the meet 10 million units by the end of the year, they will reduce the price or plan for an improved Switch

People need to stop with the "it was just bad name, and marketing", thats not fully truthfull, or even half the truth of it.

The gamepad (price) & software draughts where much more hurtfull than its name or marketing.

A "Wii 2" would've underperformed/flopped too IMO.

That whole brand was sinking like the Titanic.

you are 100% right I could easly add 3 more reasons, Controller, price and lack of proper harddrive, and I am sure people could add 10 more and they would all be right, lack of third party support is proberbly one of the biggest reasons, however.

There are pretty much over 10 reasons the Wii U failed. Collectively, those lead to its fate. Marketing was obviously an issue but diehard fanboys sometimes claim that it was just marketing (because y'know, the Wii U has the best games!)...just Nintendo couldn't advertise it!

At this point, people need to realize third party > first party. If this wasn't the case the Xbone would've never outsold the Wii U. The fact that Nintendo failed to deliver a proper Animal Crossing, bring Pokemon, get a good Zelda ontime, have a groundbreaking 3D Mario...all hurt it in the long run aswell. They only nailed it with Mario Kart 8 and Splatoon (but it came too late). Smash was on the 3DS which gave people a reason to not buy a Wii U

Animal Crossing, Zelda, Pokemon weren't even one of the top 12 selling Wii games. 

Wii Sports, Mario Kart Wii, Wii Sports Resort, New Super Mario Bros, Wii Play, Wii Fit, Wii Fit Plus are the best selling Wii games. Mario & Sonic Olympics sold the same as Twilight Princess basically on the Wii and more than Animal Crossing, lol. 

When the casual/mini-game fad bubble burst .... Wii U/Wii 2/Wii HD/Wii Super Duper was screwed no matter what. 

One thing that gets overlooked too is Nintendo utterly failed after Wii Fit to create another casual hit break through that was genuinely new. Wii Music underperformed big time, Vitality Sensor never came out, Nintendogs + Cats sold a tiny fraction of Nintendogs ... the warning signs were all over the map that Nintendo had no control/no insight into the own audience they had birthed. 

A fad-based console trend was always going to have an ugly downside. I mean yes, Nintendo made a bunch of dumb errors on top of that, but the central problem was always going to be a huge problem even if Wii U had say a better 1st year lineup or better TV commercials. 

Still have mine. Still play it. Still love it.

The problem, in my point of view: The Xbox 360 and PS3 released in 2005 and 2006, respectively. The WiiU was an Xbox 360 with less features, games, and stability 7 years late with a gimmick
controller.

Truth hurts.

There were some games that were made better by the second screen but none of them were gamechangers. That's why I think it failed. They never gave us that "You need this. This is the future." experience that we wanted.

So you think that the name was the main reason for the failure.

Although the wii brand was losing its ground, I still think the U part of the name was also a big part of the problem as a wii2/wiitoo/wiitwo would have been much more easily marketed and at least would have been seen as a new console. The brand could maybe have been saved and at least it would not have been as big failure as it now was. It might have most likely underperformed when compared to Wii, but it would easily have been a lot better.

Those of you who think that the biggest reason for the failure was software droughts or lack of huge 3rd party games are thinking the whole thing from a gamer perspective. The poor name and bad marketing also caused 3rd parties to withdraw their support (which was decent at the start) and that really happend after the Wii U sales plummeted down.

No I think continuing the Wii brand was entirely the wrong move. Not just the name, the entire concept of the brand ... basically using casual mini-games to sell a platform + some Mario thrown in. 

And yes Wii U did adhere to that formula ... look at it's release list

Nintendo Land, NSMBU, Mario & Sonic Olympics Sochi, Game & Wario, Wii Fit U, Wii Party U, Wii Sports Club, Sing Party, Just Dance ... were all available in year 1 and these are actually sequels to the biggest selling Wii games. Go and actually look at the best selling Wii software .... it's not Zelda or Metroid or Xenoblade or even Animal Crossing. 

Once the mini-game fad burst ... Wii 2/Wii U/Wii Willy Nilly ... they could've called it whatever they wanted. Once people got sick of the whole "shake the controller around like a goof for 2 minutes and play with grandma! Isn't this so much fun!" thing got old and formulaic, Nintendo was fucked with the entire Wii concept no matter what. 

They could've called it Wii 2 or whatever, it wouldn't hav made a difference. 

Thankfully for Switch, they realized this and 1,2 Switch is only a support title and not something that they are making as the main draw.