Laying directly on the seams subject them to friction from rolling over and such, and to the possibily of snagging a seam on a zipper or something. For me, it was enough of a concern to move them to a place where I don't lay on them. Except for the small part at my thighs on the second version, which will have the top of my CCF pad covering it.
Be sure to use large zigzag stitches to compensate for the stretching of the hammock body. But this also makes it more vulnerable to friction and snagging.