When I have had to wash some of my antique quilts I hand washed them in the bath tub, blotted out some of the excess water and then laid them on a sheet on top of the grass. Then covered with another sheet in case of bird droppings. Obviously, have to wait for a "perfect weather" day. I like a little wind and don't place them in direct sun. So because the quilt has not been compressed and wrinkled in the washing machine, it is not wrinkled after it is dry. Now that I am making quilts, I prewash most fabric, then machine wash and dry when completed. Because I plan that they will be used, I want to know that they will stand up to washing and drying, check for loose seams, etc.
As far as line drying, I do have a clothes line and enjoy hanging out some items. I grew up hanging clothes outside. The reality is though, that most machine washed item will dry more stiffly and wrinkly than they will in a dryer.