This constantly repeated statement is ridiculous.  GC didn't fail because it had similar power to PS2.  If failed for many reasons, such as being purple, having baby DVDs for media, Toon Zelda, Sunshine Mario, the juggernaught that was the PS2, etc.  But being powerful didn't hurt it in any way.  Your statement is like saying Microsoft shouldn't try making a system as powerful as PS5 cause we all know how the original XBox sold.

It only appeals to Nintendo loyalists and it comes down to third party appeal and support.

1.As it arrived half of the games about to be released were exclusive to PS3/360/PC (Borderlands 2, Crysis 3, Dishonered, Hitman, Resident Evil 6, Tombraider, Bioshock, GTA5). This essentially made it impossible for ps3/360 owners to seriously consider it as their next console if the majority of the games releasing weren't coming to it.

2.Even if it had all the support under the sun, said games wouldn't be appealing on the system because the system wasn't a notable leap over PS3/360, no point to upgrade. Equally third parties aren't stupid so they clocked onto this, hence why only the typical deep pocket/money hungry names (EA/Activision/Ubi) bothered with Wii U support. Everyone else gauged that their audience wouldn't have a strong interest in the Wii U and would wait for PS4/X1, so the its a vicious cycle.

3. Even had it had power+support theres then the question of branding, Wii U would have been a hard sell to core gamers after the "fad" of the wii, the family orientated image and the lack on recognisable online space (PSN/XBL)

4.If the Wii U's gimmick was strong enough it could have overcome this issue and maybe at least been designated secondary platform, but its not unique enough and was too expensive for people to buy on a whim.

It's a product consumers don't want. Simple as that.

Lack of public knowledge on the product.

If you think that it was natural for the Wii to sell 100 million.... as if it sold that much because gamers (and not an army of casuals) propelled it to the top, then of course you think that the Wii U is a failure.

Considering that Nintendo does everything possible to make sure that gamers and developers alike wouldn't be interested in the console; it is remarkable that the platform is doing this well.

My friend still has his Wind Waker HD edition still wrapped up. And he is a Zelda fanatic. Now is is considering getting an Xbox One or a PS4.

Exactly, it didn't hurted it but it didn't helped either. We all know that image plays a big role on a console purchase: a cool console, a cool brand, mature looking games. That is the key for success

Thread number 78,983 trying to figure out why the Wii U failed... there are many reasons it failed. From poor name choice, bad marketing, betting on the wrong audience, price being too high for what it is, HUGE droughts, countless delays, among others. There's a lot of reasons it failed and will probably go down as one of Nintendo's biggest failures -not to say it's bad (not a fan of the gamepad) but it had too much going against it to succeed.

I think it's a lot of things compounded rather than one single reason. Horrible console naming is a brand issue amongst kids. Kids hitting 8 and up don't want Nintendo in their house. They want to play COD with their friends and care about it being a cool console thats powerful (whatever powerful means to them). 

The first party lineup is rock solid but the tablet controller does suck as it weighs a ton and a lot of gamers were horrified seeing a tablet in their gaming device.

Nintendo also doesn't understand it's customers at times and pushes so much for innovation that it's gotten a knack at alienating it's consumer base. The sheer volume of people I knew who went 'I'm done' when the Wind Waker was announced massively harmed the GC console, and while WW is one of my favourite games of all time the look switched off the mainstream. The same thing happened again recently when a couple of my friends loved the Zelda 2012 trailer and were going to get Wii U's when the realistic Zelda launched. They'll never get it due to the new ones looks. (Personally I can't wait for it)

Nintendo until they switched to the direct E3 format could have an amazing E3, or be the worst show of the big three. During the Wii days a lot of damage was done to them trying to flog garbage like Wii Music and casual games while the core audience withered away.

I love Nintendo, they make the best first party games for me personally, but they have only in the last few years started to accept their issues. The Wii U itself was not enough, they tried to cling onto the casuals with the name, the gimmick controller, launching Nintendoland with it and underpowering the machine and they're paying for it big time now.

Weak hardware is 100% one of the biggest issues. No one is saying that thrid parties literally couldn't run games on Wii U, its that no one would want to play new games on very dated hardware. Its the very reason PS3/360 software sales are terrible right now, just look at BFHardline, AC rogue etc.... its why PS4/X1 games and hardware sold so well despite 90% of big releases being cross gen and available on old consoles people already have at home.

When discussing the gamecube you have to acknowledge that  before it had even released the PS2 has already won the generation by a mile and taken the majority of the pie. If theres a blindingly obvious console choice, people are going to go for it. Why exactly would anyone buy a Gamecube over a PS2 when a PS2 had all of this before the gamecube was even available in stores:

GT3 A-spec (15m)
Grand Theft Auto 3 (13m)
Final Fantasy X (8m)
Metal Gear Solid 2 (6m)
CRash Bandicoot Wrath of Cortext (5.5m)
Tekken Tag (4m)
Jack and Daxter (3.7m)
Devil may Cry (3m)
+
Dozens of third party exclusives soon to be release
+
Fully backwards compatibility with 100m selling PS1 and an Affordable DVD drive.

Just look above and imagine that was the PS4 with all that content and the Xbox One was only just about to be released. The sales ratio would look very similar to the PS2 versus Gamecube. The OG Xbox was limited by the same factors, it did itself a favour in differentiating through online play+being the most powerful and PC ports.

1) Nintendo's bad image from the Wii generation
2) The bad reputation of the Wii (not anything to do with confusion, just bad image again)
3) No real target audience other than Nintendo fans
4) Bad marketing all around
5) Failure to sell the Gamepad concept.
6) Too expensive
7) Barren launch
8) No third party support whatsoever
9) Simply not enough games releasing in general
10) Japanese losing interest in home consoles

It was a perfect storm of failure. There was no chance the Wii U was going to succeed, it was doomed from day one. What needs to be seen when the NX is revealed is how Nintendo plan to take on all of these challenges above to make sure the same thing doesn't happen again.