Games are cheaper, better support, same hot first party titles coming out. Why should people look at the Wii U over the 3DS? Mario Kart and SSB is going to be on both platforms. Nintendo didn't help a thing there, but also ensured high sales for those games at the same time.

But we can see no cannibalization in the data. You can argue the outcome of the similar libraries all you want, but the real outcome is already in the data.

The Wii U is selling much worse because it repelled all the Wii customers and struggles to get the Gamecube custmers onboard in a severe economic decline. This because it went a crazy direction that didn't expand on anything the Wii had achieved. It is more similar to the Gamecube than the Wii. Only the economy now is much worse, and the industry, like EA have become bold enough to think that they can move in for the kill and freeze out Nintendo completely.

This analysis in consistent with the Wii U selling bad, plus it doesn't require the Wii U taking sales away from the 3DS after the Wii U launch like your position does.

You made some points but I think the 3DS isn't the WORST enemy. Because with your logic in generation 7 the DS and Wii should have hurt each other, too. But both systems were the best.

So that means we should look for some other reasons. Both Wii U and 3DS sold bad at the beginning but the 3DS managed it to find a lot of fans. For comparison we can say that the 3DS is a better DS and the Wii U is a better Wii. The better DS sells better than the better Wii. And why? Because of the oppurtunities. Vita or 3DS? 3DS because of better games! But the Wii U has not only one weak enemy: it has two of them with the PS4 and the Xbox One and this time the Casual gamers won't help because they are saticsfied.

Of course there are other reasons like the bad advertisement or the misunderstood Gamepad. And I also think you are right when you say that the 3DS is also an enemy but I don't think it is the worst.

People dont think things are bad just because they are bad, there is always a reason. People just dont like it is not a legitimate reason, why dont they like it or see it as a worthwhile product? That is the question we are trying to answer.

I believe that a major reason is the hardware features and software is too similar to the much cheaper 3DS which also has many other big titles not available on Wii U. There are other issues as well like price in general, too many droughts in between big software releases and lack of affective advertising.

Cannibalization is in the data; with similar offerings, the cheaper 3DS sells more.

Wii U isnt taking sales away from 3DS, not sure what makes u think thats what im saying.

The only way I'd consider the 3DS the Wii U's worst enemy, would be in that when Nintendo should have been ensuring games like Pikmin hit their deadlines, they diverted all their resources into the 3DS to save that instead.

Now you've got the reverse with the 3DS having much slimmer pickings whilst most of Nintendo's resources are being pumped into the Wii U, however the 3DS was lucky, while Wii U's reputation looks to have been irrevocably damaged to the point where it doesn't matter what Nintendo do now.

They are definitely losing sales from me. There are lots of games on 3DS that I would love to play, but I do not want to purchase the handheld as I cannot stand playing on a small screen looking down at my hands all day. They can easily resolve this by doing one of the following:
1) Make 3DS games available for purchase on the Virtual Console (and make them available to play on 3DS as well)
2) Create a device similar to the Super Game Boy and let us play 3DS carts on the Wii U.
3) Allow the Wii U tablet to be replaced by the 3DS and let the 3DS play full-screen. (For the next revisions I guess)

Seriously, make it happen! Man I want to play some of those great games. They just need to unify the library and allow cross-buy/play and all that goodness.

I think ur dream may come true next gen, all signs are pointing to Nintendo unifying the handheld & home consoles by releasing devices with the same architecture and similar enough specs so they can play all the same games as one another.