Quilt collector, judge and certified appraiser Gerald Roy wrote exactly about the subject of over-quilting in the January/February 2009 issue of Love of Quilting magazine. On page 14, he says, "At the show I was judging, I saw many quilts that visually were overly designed, had distorted surfaces, and displayed quilting patterns that were too busy and complex."
Earlier in the article he states, "Just because you can, doesn't mean you should."
Good common sense advice.