It is down to art style though, It's easier to make Zelda look better because it's art style is less technically demanding. It's a poor comparison to make when trying to determine if the Witcher 3 port could have been any better than it actually is. How good Zelda looks is irrelevant.
It doesn't have to be Zelda then, even Warframe looks much better on the switch than this, with far more things going on. I'm saying that it doesn't look like they tried very hard. There's no reason the cutscenes need to look so bad, the switch can definitely pull out better graphics than that.