I have Only pressed seams open for making clothing or doing a wallhanging. I would not want to do this for a full bed quilt due to the stress of use and laundering.
Someone on this board mentioned taking a class from Kaye Wood how suggested not pressing seams. Perhaps that is her reason not so do so, as at time you have to flip seams and if pressed, you could looses 1/8 inch off the seams. So I will try her method to see how this goes.