Part of Nintendo's problem is that now, unlike in the past, parents are playing games, too--and they're the ones buying the console. It looks like Nintendo's strategy is to go after families where only the children are interested in video-games. It's a market, sure, but that still seems short-sighted.
Their problem will always be the same. The system lacks diversity. Those who are after a variety of games, whether it's because one person likes different games or because different people in the household have different tastes, the end result is that a system like the Wii U becomes a niche product.