The purpose of the waking foot is to make your machine an even feed so the top and bottom fabric go through at the same interval. Without it, the bottom fabric advances slightly more than the top. That is why, if we have a bit too much fullness, we put it through the machine with that part on the bottom. If the walking foot has a wide area there is no reason not to use if for decorative stitches. Craftsy has a couple of classes to highlight its use in embellishing quilts.