Switch is around PS3.5 level right? What you saw today is stuff that would normally be 3DS games. Mario & Luigi, and Zelda 2D. They look about like you'd expect for smaller AA stuff. Metroid is one of their bigger titles, and it looks like shooters you saw on the the late PS3 era, which is what everyone should have expected. I'm sure all the games look fine when playing them. Nintendo puts a lot of polish and attention to detail in their games in other ways.
Switch 2 is when I think things really start to change for Nintendo, because if they're about on the level of a PS4 next gen, a lot of current gen games are still about on that level so things will get very interesting.