There's this little war called "World War 1" which resulted in the absolute collapse of the final world-power level monarchies.
As it turns out: the problems of monarchies is innate. Hereditary Monarchies lead to a separation into "Noble" vs "Peasant" classes, where Nobles have a genetic line to the throne. The Nobles believe themselves to be superior and start putting themselves into various sections of government, when in actuality many Peasants are actually better than the Nobles.
So when it comes to War (the only time societies can directly compare against each other), the side that has a bigger recruitment pool (ie: Peasant commanders, aka Napoleon's secret sauce), tends to win. This is also true of sciences, research, production, etc. etc. Every part of society, there are likely peasant leaders who are best at the job.
Peasants win not necessarily because Peasants are smarter, but because peasants are at "sometimes" smarter, and this "sometimes" happens in a large enough degree that anyone who cuts off their leadership pool into "Family members of the Monarch only" innately hampers their abilities to lead over time.
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Now colonial rule by far-away foreign powers is clearly a bad situation as well (as Britain's control over its former colonies can likely attest). But that's not "Democracy" either.
Hereditary monarchy may be an improvement over UAE's position (ie: better than foreign colonialism), but lets not get ahead of ourselves. The world gave up on monarchies over a century ago for a good damn reason.