Whenever I have made matching shams I do quilt the top part of them. I think you will find with no quilting you will have a wrinkled mess with every washing, at least that has been my experience with under quilted items like placemats or the one time I had to wash a quilt top prior to quilting. Additionally I think you will be much happier with the finished look with, at the very least SITD quilting. Shams are so easy to quilt because they are smaller and even an all over cross hatch looks good.