I think Kaprow is trying to say that the little motions we do on a daily basis, such as brushing our teeth, are not seen as traditional art, but are seen as more natural, personal kinds of art that can't be displayed in a gallery for all to see.
I believe that this reading will broaden our minds so that we can think more in depth about artwork, and more specifically our artwork. It will help us analyze the littlest details and really make them stand out in our work, which in return will make them that much more powerful to our viewers and to ourselves.