As I said earlier, the gameplay does seem much nicer now. Single Player is still higher resolution if that matters to you, but with this art style it's hardly necessary.
For those wondering what the problem is, though, do remember that this is a launch game... think back to the recent launches of the PS4 and Xbox1, for instance, and you'll see that consoles tend not to show all they're capable of right out of the gate.
We already know from other games that the Switch is capable of more, but there's probably a reason that goes beyond the understanding of most of us as to why this game is having issues with higher resolution.