Very interesting post! I don't have much to add except that towards the beginning you gave me an urge to write a fic in which people say "what?" and "huh?" a lot until I got to the part where you basically said a fic like that would probably suck.

Also this: "But instead, I have just as much trouble expressing myself through my body--lots of time people think I'm angry when I'm not; when I'm at my most sincere I'm often accused of lying; and when I'm sad I've never once had anyone ask me what was wrong due solely to the emotion writ on my face" made me go "this is so me!" but as you said, that's probably the case for a lot of people. Personal specific examples: I remember very often in high school I was accused of looking really annoyed when I was merely amused, and when I was growing up, my dad consistently interpreted my "bored" face as "worried."

Personally, though, I wouldn't like for people to automatically see when I'm sad, because I prefer to keep that stuff to myself until I'm really ready to share. That's something that I love in fiction, that I think is better in fiction, that I wouldn't want to transfer over into the real world. Always having silky hair and great sex, on the other hand...