The reason is says wrong side up, is because when you "bind" a quilt sandwich, you don't make seams and turn it back rightside out. You simply bind the raw edges, with the batting sandwiched between the top and backing, and so both "right" sides are already showing. Both sides will be pretty, and it will be reversible.
If you're going to skip the binding and seam the front and back, like a pillowcase, then turn it rightside out, then yes, you will put the "right" sides together.