The Gathering Storm, Churchill's memoirs of the Second World War (p. 10), has a good explanation of why the Allies kept the emperor, by way of the cautionary example of Germany after the First World War.
"Wise policy would have crowned and fortified the Weimar Republic with a constitutional sovereign in the person of an infant grandson of the Kaiser, under a Council of Regency. Instead, a gaping void was opened in the national life of the German people. All the strong elements, military and feudal, which might have rallied to a constitutional monarchy and for its sake respected and sustained the new democratic and Parliamentary processes were for a time being unhinged. The Weimar Republic, with all its liberal trappings and blessings, was regarded as an imposition of the enemy. It could not hold the loyalties or imaginations of the German people."
Interestingly, Churchill ends almost every sentence of this passage with a prepositional phrase beginning with "of." "Of the German people, of the enemy." He borrows this structure from Edward Gibbon, as Churchill himself noted. It helps to give weight and finality to the end of his sentences. Note too that Churchill almost always chooses concrete, action verbs: crowned, fortified, opened, rallied, respected. It makes the sentences more active and their imagery more vivid.
Edited by CrimsonSox - 2/12/14 at 12:14am