Something that comes to mind when creating new breeds or crosses: chickens are considered food, dogs are not (at least in this country.) So breeding tons of chicks to get specific traits doesn't really add to an overpopulation/not enough homes problem like it does with companion animals like dogs. With chickens you can eat your culls. Some shelters put down puppies by the wheelbarrowfull.
I'm not against responsible breeders breeding dogs; they know what they are doing and do it for love of the breed, not money. Yet there is so much irresponsibility out there, it just irks me to see people creating mutts on purpose and selling them as some wonderful new breed. When there is no need for animal shelters, because there are too many good homes, then I'll change my mind.
BTW, I prefer mutts over purebreds too, and I look for them at shelters/rescues.