First and foremost was the marketing. Absolutely agreed and I've yelled about that a few places online already.
When you compare them to Xbox and PlayStation, that's all Sony and Microsoft have had. Those are the brands for their gaming consoles. So adding numbers and letters to those implies more than what Nintendo did with the Wii U name. Given Nintendo's history you'd think they would have created something new entirely. But of course it also helps moreso that MS and Sony have ridiculous marketing campaigns.