To have a purpose
Story telling, instructions (i.e. pattern making, recipes, etc.), archive (just about anything from history, weather, daily activities, etc.).
It stops pens and pencils feeling bored.
Explorations of the creativity networking in the mind.
Do you think she had to keep from facepalming while asking the question?
Writing has a variety of purposes. To provide entertainment, information, to pursuade someone of something, to communicate, to help something think things through and a plethora of other reasons.
Some words are not enough to express the value of few things in life writting is one of them
Helps towards clear thinking among many other reasons.