I think a lot of the cotton vs. cotton/poly hangs around from the 'olden' days. A lot of the same ideas for cotton only fabric vs. cotton/poly fabric. There were very valid reasons when we washed things in very hot water and there was a very big problem with shrinking. Also, the quilts were made to last forever and be passed down. Today, most people wash most things in either warm or cool water so shrinkage is much less and as sad as it is, our quilts are not going to be kept forever. So, many of the old rules don't really apply today. I think it is more a personal preference and how you were taught that is the biggest influence today. The only time that I plan on using all cotton everything is when I make a quilt for an infant. Because I know this will be washed in very hot water, will probably have many staining stuff on it and may even need additives in the wash water. Poly tends to hold onto stains. Like I always tell my students - it is your quilt, you decide what you prefer to use. Olden days crazy quilts had bits of velvet, lace, cotton, feed sacks, satin, everything they could find in them and they are still around!