A very engaging proposition, doctor. While I am a fervid proponent of the idea that a strong, centralized power does wonders for order, unity, and tradition, I must offer this in reply.
While I cannot argue that training and example from birth is invaluable, it is much more difficult to instill charisma, which is needed to inspire a people. Perhaps long-lived loyalty and nationalism can be substituted for a time, but not indefinitively. It is my belief that even on a ruling council, one will naturally rise above the rest in influence, not legal power, and become a bastion of popular affection and loyalty, from which flows prosperity.
On that note, the success of a monarchy depends on the monarch. A poor monarch can do just as much to cripple his people (denying any help that might sway his people from him or challenge his authority) as a good one can to prosper them. This need not be tied to their kingship, but by their ability.
So then, while a strong, centralized power offers much benefit to the masses, a Monarch can only be removed by abdication or revolution, which is a determent to the people. In its place, I offer that natural leaders rise in governing bodies to lead the government on, and therefore the benefits of a monarchy need not be exclusive to the presence of a ruling lineage.