Emotions in written communication

Written communication is not a patch on face to face communication, they say.
80% of all communication is non-verbal, they say.
Why then do we cry or laugh when we read books?
If an author can evoke such emotions in a 'broadcast' mode, surely when you send an e-mail directed to a particular person you should should be able to convey all your emotions even better.
And surely, emoticons are not the only way to convey your emotions.
Think about it.