Nintendo does tend to go after the younger audience. Just a fact. They also go after the core audience as well.
The difference is just percentages. If Sony and Microsoft are 80/20 core/casual; then Nintendo are 60/40. Or 70/30. But you get the point.
And also, just because something is colorful with great art style and no blood does NOT mean that it is a casual game. So while Mario 3D World looks "casual" to the mainstream, it's a core game. Hotline Miami meanwhile is a casual pick up/play game. You get my point.