I would imagine it would hinge on the simplicity/elegance of the organized structure of the APIs? We tend to prescribe the term beauty to language features that are easier to use and implement in a novel way compared to the languages that came before.
I'm not sure that is the same use of the word "beauty" as used in copyrighted materials like books and art, since APIs are machine blueprints, whose primary and fundamental purpose is functional, not aesthetic.
Similarly, though a mechanical engineer might describe a particular gearbox design as beautiful doesn't make it copyrightable, since it's fundamental purpose is also not aesthetic.
