Nintendo just does the portable versions first. New Super Mario Brothers was on DS, then home consoles. Mario 3D Land was on 3DS before WiiU got 3D World. Smash Brother is coming to 3DS and months later the WiiU version will come out. In each of these cases the portable games will be superseded by better home console versions in the same way you suggest Vita games are, Nintendo is just better at tricking people into buying both versions anyway.