I wanted to add also that many vintage quilts were quilted very closely. One of the reasons they remain soft to the touch is because traditional cotton batting was used -- which is thin, made without scrim or needlepunching. (Mountain Mist Blue Ribbon batting is an example of this very traditional cotton batting.)
Machine quilting puts double the amount of thread that hand quilting does into the quilting lines, though, so that needs to be taken into consideration. This is one reason why using a finer thread for machine quilting helps with the softness factor.