Miyazaki himself dislikes most anime because most of the animation reference is based on other anime and not real life:
http://en.rocketnews24.com/2014/01/...strys-problem-is-that-its-full-of-anime-fans/
Edit: I'd have to agree with him. Body language, even if it's from another culture, is natural and shouldn't have to be explained to someone. Even if it's from another culture, if it's real body language, you should be able to interpret and assume some things. Otherwise that's not natural body language, that's just a weird thing that someone does that's not communicating anything correctly.
Animation is fiction, having non realistic body language is fine as the characters don't actually exist and can be set to do what they want within the boundries of their own world.
Fiction would be really boring if everything was super grounded in reality.