Why are beauty pageants seen as a big deal for nations? And well showing of gorgeous women in general in events unrelated to pageantry like international diplomatic negotiations and catering food services to foreign soldiers stations and other big national stuff?

In the novel Anna and the King of Siam, the Siamese King's diplomat thought it important to impress the British diplomats by taking some beautiful palace servants, dressing them in Western fashion, and training them in dignified mannerisms as seen by British people.

So it provoked me the question- why do nations make it a big deal of choosing beautiful women as representatives and dressing them fancy along with making them learn appropriate etiquette and "high class" behavior? Not just in pageants but whenever they have diplomatic meetings, business deals, and other stuff do they always pick women who are the cream of the crop or at least take stunning women commoners (if they decide not to use the 2%) and train them to be regal in behavior? Is this a big deal in realpolitiks?