I completly agree. We often forget that an API is still an interface, and it is often more a designer and part that a technical part.(but still a technical part or maybe a cultural technical part) In Real Life, product interface design or service interface design is often better made by external desiner that focus on understanding OBJECTIVELY how users will and want interact with , than the original producer or provider which will be affected by what he wants to expose and its history and vision about his product.