What's the point of a designer putting a design in a magazine, if they don't expect people to make quilts from said design? What real difference does it make if the quilt is being made to give away versus showing it in a show? Seriously. What difference does it make to the designer?
Copyright's real intention is to make it so that the copyright owner has control over the distribution of copies of their material (i.e. the "right" over "copies" ). By putting one's design in a magazine, the designer is already giving implicit permission for copies or derivative works of their design to be made (otherwise, what's the point of including instructions, etc??) To then attach strings to that by saying, "Well, it's okay to make a copy of this design to give to your cousin, but don't make a copy to put in a show," really makes no sense. A copy is a copy is a copy. In what real way is the designer being harmed by one of those copies being displayed in a show, versus another copy hanging over the back of a couch?
The real harm to the designer is if someone makes copies of the instructions. But that's not what is being discussed here.
(and yes, I wholeheartedly agree that any quilts made from designs from someone else should include credits to the designer. Having to ask for permission, though? Makes absolutely no sense.)