My feeling is that it is about convenience when typing at the terminal. Having a unified language for both scripting and entering commands is quite convenient. Also, bare strings while typing at the terminal is very convenient! It would be really annoying if we always had to add quotes for string args when we're typing at the terminal:

  $ cat "file.txt"

...and I don't even know what options would look like... maybe:

  $ ls "*.txt", ["l", "a"]

I dunno... this would mean we'd probably need parens now for precedent-type concerns:

  $ ls("*.txt", ["l", "a"]) > "file.txt"

Anyway, that is why I understood that it's this way. I can't point to a resource about it, though.