Traction is one, kinda importante, but we can safely asume that WiiU, PS3, 3DS, Vita and XboxOne had other much bigger problems.
1. PS3? Terrible price, anemic launch and too late compared to the 360, when sony announced the price, 360 was already on the market and much cheaper with a vast amount of software to support it.
2. 3DS? Comparable situation to the PS3, the price and launch software BUT there was also marketing (which also leads to WiiU), the 3D was a super gimmick (that just like their TV counterpart) it never really took off, so it was an expensive machine that had a cool gimmick and that's about it.
3. WiiU? Marketing, it was all about the marketing in that one, it was terrible, a total disaster, that and that the Wii was dead like 3-4 years ago and the Nintendo brand wasn't the strongest.
4. Vita? I'm not sure why the vita failed so badly besides the stupid memory card prices.
5. Xbox One? PS3 all over again, terrible price (more expensive than the PS4, quite a wide margin) and we can't forget the disaster that was the presentation. That presentation alone killed it (And Kinect).
Software is super important, and traction can help you get a dedicated fanbase, but i think it was mostly down to pricing and marketing, especially the later.