Nintendo Land, NSMBU, Wii Party U, Mario 3D World, Mario & Sonic Olympics, Scribblenauts, Pikmin 3, Game & Wario, LEGO City, Rayman, Sonic, are plenty easy for any kid to play.
The reason iOS/Android is eating Nintendo's lunch is because the games are 99 cents and its making parents reconsider buying a Nintendo console/handheld at all.