Writing is easy to define. Of course, "basic writing" is a little more abstract and semantically disputable. It could be described as the most basic writing. But, I prefer to see it as a jumping-off point to greatness.
Basic writing is a tool which can be used to find out where a writer stands. It can be used to show strengths, identify areas to improve or simply to help the writer gain confidence in their own writing. This last point is essential for the writing process. Those who lack confidence or motivation need to be comfortable with writing and develop a technique for writing which will help them to best communicate their ideas.
Basic writing is a testing ground which allows the students to explore different modes of writing to find a comfort zone. Basic writing encompasses everything from personal narrative to opinion paper. The topics vary widely. Of course, the subject matter is rather elementary, but it challenges those who do not write on a day to day basis.
Basic writing should challenge writers in order to make them think about their work. In this way, the writers think about what words to use in order to express different views. The writers can see that some words are stronger than others, and how their words can reflect a constant voice.
Basic writing is an exercise in writing. Much the way atheletes stretch out before a big game or work out in order to stay in shape, basic writing is key in the writing process in order to warm-up the brain for bigger feats and challenges.