Again, Yes. It's meteoric rise and fall and complete inability to maintain itself within the market (that it controlled with a commanding lead) is evidence of this. The Wii U's abysmal performance so far is just further indication that people moved on from caring about "The Wii" several years ago and the 'fad' wave or public spotlight is clearly gone. The fact that the market and industry never supported it just aids in the belief that everyone felt it was a fad and weren't willing to invest into a fad.
The reason the PS1/PS2/PS3/Xbox 360 etc were not 'fads' is primarily due to the fact that they kept the 'standard' formula that has proven time and time again that it sells and is wanted. The same reasons that Nintendo fans beat their chest about how 'innovative' Nintendo was, is the exact same reason that what Nintendo did was completely a fad. Much like Lady Gaga wearing some new crazy wardrobe and other people following suit.
Motion controls were a fad (A point even furthered by the copying done by Sony and MS), hence Nintendo's biggest selling point was a fad and the console was proven fraudulent at that point and that's when it started to die on the vine. It's really that simple.
In my opinion, the Wii was one of the most fraudulent, fad-ish consoles that has ever existed and certainly that Nintendo has produced. It lived off of pure hype and had one of the worst Nintendo libraries with poor gameplay often times.
It sold off of motion control hype, price, name brand. Once price point power disappeared and the hype faded it was dead.