Seeing as Nintendo themselves (1st party developers) have only developed one "traditional" FPS (traditional in the sense of Halo/Doom/etc.) in their 100+ year career, I don't see why the reasoning for this phenomena would be "they're not hardcore enough/their new casual appeal/etc.". It could be... could be that they've never been that sort of developer to begin with.
(NST developed Metroid Prime: Hunters if anyone was wondering.)











