I am not interested in arguing for the house of Windsor. I am arguing for monarchy in general. The best king Britain ever had was Charles ii, who resisted the encroachments of a Whig parliament with designs upon the rights of the poor. That has always been the job of kings, and Charles Stuart ii, smeared as absolute monarch (by a Whig plutocracy dying to do exactly that) did a magnificent job and in many quiet ways rescued the British constitution and the rights of the lowborn.
Furthermore the concept of social immobility in which there’s no possibilityof advancement for the lowborn, is at odds with history. People didn’t come to America for freedom as a concept; most came to get rich quick in a land with no rules, or else to skip out on their debts.
The modern world though created new and far greater sources of wealth and national power based on mass education, science, commerce, and industry. World War I then discredited Europe's governments, exposing them as ready to butcher their populations by the millions rather than accept a loss of national stature. With the exception of Britain, Europe's monarchies -- most of them run by dolts -- did not survive the conflict and its aftermath.