The thinking that crystal malts are bad sort of started when Vinnie Curlizo said they clash with hops. That's what people heard.
More accurately he said the higher Lovibond crystal malts, C60 or so and above had dark fruit flavors such as raisins, plums, and dark sugars that would clash with piney and citrusy hops. He advocated using less that C40 colored crystal malts which are mainly sweet.
I wonder how the new fruity hops would go with a dark crystal malts?