Without looking at it, I am going to say that good breeders in most breeds work to prevent health problems, not breed them in to their dogs, but in some breeds, this can't be done without changing the winning type, and often judges are so stuck in their ways this is impossible, so in these breeds the descision needs to be made of dogs that "look like they're supposed to" or dogs that don't, but are healthier. And to use a blanket "well the healthier type" reasoning doesn't work without taking into account a whole lot of reasons.
Many breeders do not use the health tests available to them when selecting stock, and the kennel club does not insist that they do so. It recommends that they use them, but doesn't insist - even for its accredited breeder scheme! And many judges take no notice either.
You're right, Nutterly. A dog's conformation precludes health in many cases - when a BUlldog's head is so big it can be born naturally, or a dog's face is so flat that it passes out in any heat whatsoever or after walking a short distance. Perhaps this is why the BBC is saying it is reviewing its Crufts coverage - because showing is so intrinsically about health nowadays and not health.