Just a wee bit of clarification - AKC does not prohibit the breeding of fluffs and two AKC registered PWC or CWC parents can produce a litter of AKC registerable fluffs. So yes fluffies can be bred and there are breeders of dubious regard who do breed specifically for them and will market them as "rare long haired corgis." I know of at least one current CWC breeder who has been known to utilize coated dogs in her program. Additionally back in the days when gene pools weren't as large, fluffies along with mismarks were sometimes used in a breeding program to reach the next step. The gene for fluffies is in the genetic soup of the breed(s) and by the nature of its inheritance, it isn't going away. Fluffies will most likely always be with us.
The standard describes the perfect specimen of a breed and that is the brass ring reputable/responsible Breeders are reaching for. Each breeding is or should be <imo> approached and done with the goal of reaching one step closer to the "ideal." Since there are no "perfect" specimens, Breeders keep trying. Mother Nature always has the last word tho'
and fluffies are one way she keeps Breeders humble. I also believe that well-bred, sound tempered, healthy pet puppies placed responsibly in the correct homes are as much a credit to the breed(s) and their Breeders as the next great specials show dog, which are not always the easiest ones to live with either, btw.
Debbie