I personally believe that Nintendo like quality emerges from a holistic bottom-up approach. Nintendo lets games dictate their surroundings, not the other way around. Nintendo games are rarely reactionary, and tend to be completely integrated into what the gameplay needs, instead of what outsiders think the game needs.
Yes, Nintendo is quality, polish, technical proficiency, willingness to delay a game for quality reasons, accessible by the mass market... but more than that, Nintendo develops the gameplay and game design systems first, and the graphics, story, features, etc. of the game only later take form not to be excellent on their own merits, but merely to support the core gameplay.
This, I believe, is one of the reasons why Nintendo (Miyamoto) games will probably NEVER have any RPG-like depth to their stories: they believe that stories exist only to provide structure for the gameplay and nothing more.