I think of black & white as the classically beautiful border collie. Maybe people just want the "new" model? I think Shelties have the same problem - everybody wants a merle. I'd never even seen merles till a few years ago!
Makes me crazy with my breed too - some people are obsessed about wanting blue-eyed huskies, like having brown eyes makes them a less desirable husky. It's always a key point with advertisers who are in it for the buck -- "We breed for BLUE-eyed husky puppies.", when they should breed for "great confirmation & temperment".