It really depends a lot on what batting was used in the quilts.
Most antique quilts in this country had cotton for batting. There was no needlepunching, scrim or bonding agents available then. Quilting needed to be very close to keep the cotton batting from shifting and, when washed, the cotton would shrink more than the batting giving a slightly crinkled look to the quilt. Cotton gets softer every time it is washed, so a lot of loveable antique quilts are now not only crinkled but also extremely soft to the touch.
Lumpy quilts were usually the result of insufficient quilting to keep the cotton from shifting, especially after being washed.
Some antique quilts were made with wool blankets for batting. Usually the wool blankets had been washed multiple times before being recycled into batting. This type of blanket would not shrink after being incorporated into a quilt, and the result would be a much flatter quilt.