Pretty much this.

Heck, I'll admit, when I watched the initial E3 trailer for Wii U, I thought it was a peripheral for the original Wii.

The fact that even their E3 trailer didn't explicitly say that the Wii U was a brand new console is a pretty bad sign of their marketing if you ask me.

Wii u sell poor because they lost casuals and don't have 3rd party support

Cause the wiiu looks like a tablet accessory to the wii since the console itself doesn't look all that different in first glace where has the x1 vs 360 looks like a world of difference

Wii 2 game  (said this way " We too game") or some such, with We too something.

Would have been alot better than Wii U.

Same with NX..... just call the damn system Wii Next  :p  or  Wii 2/3 whatever.

If nintendo is trying to build a brand name, like playstation with Wii, the consol should have a modifer next to it, that differeniates it from the previous in the series.  Numbers are really good at this, and make it apparent which is the old model and which is the newer.

This. I'm not super ignorant where games are concerned, and even I was under the impression the Wii-U was a tablet accessory for the Wii up until Wind Waker (and only because I heard WW was HD, something the Wii doesn't do). Granted, I haven't paid close attention to Nintendo after the GC, but any effective marketing should have nipped the confusion in the bud.

I think the problem stems from then prefacing all the Wii peripherals (which there were a lot of) with the word Wii

Wii Balance Board
Wii Remote
Wii U
Wii Remote Plus
Wii Sensor Bar

Which of those is a peripheral for the Wii and which is a new system?

Pronouncing Wii 2 sounds like you're trying to bame a Pokemin though. It sounds terrible for a piece of hardware. Wii HD would have been beter, and quite succesfull if it hade been released earlier.

The problem wasn't the name. It was how the console was presented and marketed: everything was about the gamepad.
Even Nintendo sent mixed messages in the E3 2012 press conference. "This is Wii U". And then Miyamoto picks up the gamepad. It happened.

There was confusion, all right. And it was fair to point at that confusion as the reason that lead people to not see it as a successor to Wii.
The real problem came when it was clear that despite the brand confusion, the main market for Wii U's existence simply wasn't there. And it wasn't there even when the confusion was taking place.

You could have called it Wii 2 and things woulldn't be that much better.
Nintendo was counting on "someone" who wasn't there to begin with. MS never had that problem - even if they had called it "XB 360 now with more power" - because their market was there.

It seems clear to me that, the recipe for a good consol name is;

a) formula that goes "brand name" + "modifer"
b) works best if the "modifer" is a number (people know that 3 > 2)

The problem with the Name nintendo choose, was not the Wii part...
I can understand that theyre trying to build a playstation like brand name for their consol lines.
Its the U part, if it was just named Wii 2 it would have worked alot better.

People are used to Nintendo coming up with a new name with every console, so when Nintendo named another console "Wii" they assumed it was just a slight iteration of the same thing. I mean it even looks a lot like the previous one.

Having said that the Xbox One's name was a mistake too, but the console itself wasn't as much of a mistake as the Wii U (Overall).