Uses: Especially helpful if you feel nervous about drawing, afraid you "can't draw" or will make "ugly art." It's also useful as a relaxation technique if you are tense or tired. You can turn your head off and just fool around without any goal in mind.
This is a good way to loosen up and get started, the way dancers limber up their bodies or musicians tune up their instruments. These drawing and writing tools are your instruments and you need to know them and what you can do with them.