I agree, in principle, with what you are saying but the Beagle is a special case. Genetics in some breeds make it impossible to have a breed temperament outline as different lines have been bred for different uses. Most trainers of protection dogs, for instance, will not even consider American bloodline GSD's as they do not have the drives necessary to make the grade. Protection work is impossible for them as it has been bred out of them. This does not make a bad dog or a less valuable animal, just one unsuited to protection work.
In dogs from a working line Beagles have a pack instinct that goes way beyond the usual dog. A pack to a working line dog is other dogs and lots of them. Drugs and behaviour modification may have some effect but they will never change the genetics of the animal. People will never take the place of the pack for a Beagle with the genetics of the true working type.
Before everyone tells me of their obedient, social and happy Beagles at home they are of a different type. Just as the GSD's mentioned before are of a different type to the dogs suitable for protection work.