What good is that pretty dress doing you in the back of the closet? Get the thing out and wear it!
Same goes for patterns in your library. With me designing new patterns ALL THE TIME, adding to the hundreds and hundreds I already have, it pays to rummage through the old ones, find the neglected, dust 'em off, and switch out the colors.
Maybe with the new coat of paint, and a new upload with my agent, it will sell!