When I first learned to quilt in 1980, I was told to always wash the fabric first to test for bleeding dyes and of course, for shrinkage. However, over the years since I do not wash first because the fabric becomes limp and unless you starch it, I don't like the way it handles. I prefer handquilting because I am addicted to handwork but I have machine quilted when in a pinch for time. In my 45 years of sewing experience I have never had a problem with not washing the fabric prior to quilting. I also enjoy the "antique" quality you receive with any shrinkage.
My advice is to make a small wall hanging without washing first and then make one after washing and experience the difference. Then you can decide whatever you enjoy. Remember, quilting is a peaceful and rewarding gift.