I know this sounds stupid but why is stitch in the ditch so popular? I guess as a predominately handquilter I just don't understand. I only do that when I machine quilt and then I use a decorative stitch that straddles the seam line. The only time I stitch in the ditch by hand is if I am using a cheater's panel that looks like piecing or applique but is just printed on the fabric. I have done some of those that are fake Baltimore Alblum prints. Even other quilters don't realize they are fakes until they get real up close and personal with my work.
When handquilting an item that has been hand pieced I make sure I quilt at least an 1/8 or 1/4 inch inside the piece to renforce the stitching of the pieceing.
My thinking is that the quilting stitch be it hand or machine is what makes it a "quilt". Even if mine is not perfect I want others to know that at least I tried.