I agree that graphics on Nintendo platforms newer than Gamecube are always worse than their competitors, but it's really not what makes them a success.
They promoted amazing graphics on the Wii U, and failed.
Not saying Wii U graphics were better than PS4 or Xbox One, I mean rather the way Iwata-sama promoted it.
Nintendo is more a platform for games with a much less realistic approach, it's really more for games that are easy to understand and have a joyful atmosphere, so graphics that surpass reality is really not what they need to make.
In fact, when I play a game I want to feel like I'm playing a game, not like if I'm in the middle of a different reality, this is another reason why PlayStation and Xbox just never suit me.
But by being lowered powered by a huge amount, they effectively alienate 3rd party publishers. Hence fewer games come to Nintendo Consoles. I hope this changes and the Switch gets tons of 3rd party support.