2. If they were meant for everyday use, they were generally quilted less heavily than we machine quilters tend to do so that also lends to “softer”. Heirloom/special quilts may have been very heavily quilted but they still had 1/2 as much thread in them and were generally saved for “good”.
I absolutely wash and dry my quilts and it does help to make them less stiff. Use mild and small amounts of soap, cold water, and perhaps not dry bone dry in the dryer, lay flat on a bed to finish drying. And of course this is not something you do on a weekly basis. Also, use helps to soften them up some. I want my quilts to be used, loved and worn out eventually. Why would I need to buy more fabric to make more quilts for my family if they didn’t wear them out :0) I believe that not washing quilts will make them wear out quicker as the dirt and oils from our skin and such are very hard on fabrics.