Marketing is not the only reason. Appeal is also a reason.
Little Kings Story is probably an awesome game. But the genre and play style is just not a widely appealing one.
The thing with third parties is that they won't put the actual mainstream games on the Wii (or when they do, not even market them or take away some of the mainstream features, like Call of Duty not having local multiplayer other than the rail shooter co-op). The big exception is Monster Hunter 3, which is a hit.
The thing with the niche games is third parties and the gaming press pretending they aren't niche and the Wii is making them fail (to the point of lying that No More Heroes is a flop despite the hard, objective sales being the best yet of his career).
A flashy-first game is awesome when it comes out. A great-first game is awesome forever.
Plus, just for the hell of it: Kelly Brook at the 2008 BAFTAs
