Then how do you explain the downgrade?
BotW, a game designed for WiiU, runs at 720p on WiiU.
The same game, ported, runs at 900p docked and 720p handheld. Furthermore the framerate in portable mode is much smoother than the WiiU version.
There are other examples, but the Switch is a sizable stwp up from WiiU. I am surprised that you of all people did not know that.
As for the "downgrades", they do not look like downgrades at all so much as newer character models that differ from what you are used to. Solid Snake for example looks like a step up to me.
And seeing how this is NOT A PORT of the WiiU game, new character models with a slightly different art style makes sense. Different yes, but by no means is any of this a downgrade.