Still doesn't change the fact that it's the first time a technically high end 30fps PS4/Xbone game has been brought over to Switch. Less happens on screen, but that simply means more processing power is budgeted towards asset quality, lighting, shaders, and post-processing.
I'm just guessing and am in no way a graphical expert, but maybe that's why this port is even happening? Game is very linear, not a lot of enemies on screen, and I imagine the parts where the graphics really excel over other games (the parts I bolded) are going to be cut down significantly, if not removed. If I recall correctly, there's been a few Switch games which had to change the lighting system to compensate for the lack of power, for example.
I also have to wonder if the version shown at the direct is even the Switch version, or just what a Switch version could/will theoretically look like.