Most people know how to speak and listen in order to communicate and most individuals can read as well. On the other hand, writing is not natural and it must be learned. Generally, someone has to teach you how to write. This is not to say that there are not those who love the activity of writing, but they are rare. I do, however, find my students putting off writing as long as they can.
Writing is disliked and avoided because it is frustrating.
It is frustrating because it is unnatural. We do not think about the grammatical correctness of the utterances, nor do we think about mechanics. We do not repeat utterances over and over again to check for correctness or appropriateness. Most writing, on the contrary, does not flow out smoothly. We write a few lines, reread them, scribble out one of the lines and move on.