Comment by etanol

Spoken language is backed by other optional channels of information:

* Audio: speaker controls tone, speed and emphasis

* Video: body language

* Feedback: listener can acknowledge reception or ask for repetition

Written language has more time to be composed and it usually has the possibility of being ammended before submission.

Therefore, I always considered natural the difference between spoken and written language styles.

On a less picky opinion: agreed, complex ideas should not be written in complex language.