I wash for a few reasons - to get the vintage look, to wash out the spray basting or fusible batting stuff, I do work on my floor so there might be dirt, and I throw in a coupe of Color Ctachers as I do not prewash my material as a rule. I want the quilt to be ready to go without anyone thnking they can harm it.
Oh yes, I always wash baby quilts too so that they are softer.