Why shouldn't more countries have Queen Elizabeth II equivalents?
Why shouldn't more countries have constitutional monarchies, with kings and queens like her? Powerless, inoffensive, nonpartisan ceremonial heads of state like that are very popular in the few countries that still have kings and queens like that, primarily in northwestern Europe.
(This does NOT mean that power should be taken away from elected leaders--it should not be. I wouldn't dare suggest giving a king or queen any real power, since that would be undemocratic. Running governments should be done by elected leaders, of course.)