Today's Nintendo designs the hardware with the casual demographic as their priority.
Hardware does matter when it comes to offering better software. In this day and age, games aren't only about gameplay (as they were 20 years ago). Today's gaming is also about offering experiences.
You can have an excellent Action/Adventure as far as gameplay goes, with awesome mechanics and design, but with crappy animation, ugly graphics, unimpressive environments, archaic facial animations, no sense of immersion etc. As good as the game may be, in terms of gameplay, the experience would be weak becasue the hardware would hold it back.
Now, that wouldn't be much of a problem in platformer like Mario, where it's all about the level design, but in game like Zelda or Metroid it would make a huge difference.