For most schools, unimportant. You will want to look at each individual school's website to see which portions they consider. Many schools only consider the verbal and quantitative sections, and more schools are increasingly not considering the GRE at all. Just check each school to which you plan to apply.
I would still plan to do your best on each section. The GRE has very specific guidelines as to how to write your essays on AW section, and if you read over those you should have no problem. Even if a school says they don't consider the section, they will likely still see your score and know whether or not you at least attempted to do well.