Your interface with the hammer is your hands, so you might care if the grip is rough or slippery, apart from how well it hits nails.
Your interface with code is your eyes, so it can matter a lot how it appears. We read code more than we write, so writing for legibility is important. People talk about line noise. And we use syntax highlighters and monospaced fonts. All of this is for appearances.
My interface with code is definitely not my eyes. My interface with code is the mental structures I keep in my mind while coding. Rust is perfectly legible, even better than legible, because all the structures in my mind can be simpler since the language guarantees so much on its own. Something as superficial as wether the language uses :: or whatever doesn’t even register while I’m programming.
Also, that was a nonsense metaphor for you to use. The grip being slippery is so far removed from “beauty” that not even trying to change the subject to be about “interfacing” can redeem it.
C++ is a slippery hammer, not because it’s ugly, but because it’s easy to hit yourself in the foot using it.
Your interface with code is your eyes, so it can matter a lot how it appears. We read code more than we write, so writing for legibility is important. People talk about line noise. And we use syntax highlighters and monospaced fonts. All of this is for appearances.