In my opinion, the reason for western (not only western, eastern join this club as well) developers not support Nintendo is because they have close ties with Sony and Sony knows if third-parties left them behind to support Nintendo, they're as good as dead. Sony can't, by no means, survive only with it's first and second-party titles, so a strong third-party support is vital for them. Third-parties don't want Sony to go down, so they don't support Nintendo because it's Sony's major competitor.