The federal circuit ruled that an API is a "creative" work and thus is copyrightable. But is it really creative? It is an interface and made according some rules, not some sort of art... I must point out I have read the 28 pages ruling.
Whether you should be able to protect such a creation from copying is an issue for society to choose. So far it has chosen poorly.
I don't think that argument is a winner. Take any man-made thing, you can find some creativity that went into designing it. And that's the point -- creativity is not the sole determinant of copyrightability. What would be the purpose of the Patent Act if you could get 95 years of copyright protection just by describing invention as a creative process? Drug companies use creativity when creating cures for diseases. Should the formula or process of manufacturing for the Polio vaccine have to be licensed to this day under copyright?