Nintendo's marketing has always kinda sucked. Of the four major hardware makers of the last 20 years (Sega, Nintendo, Microsoft, Nintendo), Nintendo pretty consistently has the shittiest marketing. The Wii launch commercials were OK but it's not like they sold because of the launch spots. I don't even remember any DS commercials aside from the one with Beyonce I think.
If a Nintendo product sells it's almost always because word of mouth from consumers is very positive, not because their marketing is great.
Trying to sell an entire platform on a controller alone is a stupid risk IMO anyway. Yes it can work, so can going to Vegas and putting all your money on the roulette table to try and pay your bills. That can work ... once. Try it three or four times and see where you end up.
The other problem is a controller can be copied by anyone.
