Not always.
I've seen countless litters of working bred dogs who never produce anything I'd call pet quality. Puppy after puppy after puppy is hard core working quality.
Breeding a dog for obedience/rally/conformation, IMO, is akin to breeding for pet quality. You prove good structure and trainability in those venues. Obedience titles don't help me if I'm looking for a herding dog to work on my farm, but if I want a house pet, they mean a lot.
But those "standards" don't have to be titles. In a working dog, you really can't judge him based on five minutes in the ring. Heck, even Morgan, my least trainable dog, managed to get an obedience title. She even got two blue ribbons in the process.
There are many ways to assess breeding quality outside of the ring.
Form follows function. It's not that the leg length allowed then to perform their intended work. It's that selecting the dogs that excelled in that work created a certain length of leg or snout or ear set or eye shape.
Depends on how you're defining "aggression".
:rofl1:
But you do know that corgis are the only breed pigs will listen to.