Personally, I don't see the point.
As far as I can tell, they serve little purpose other than to give us an identity. They use taxpayers' money - often unwisely - and give very little of value back. A few appearances/openings here and there? Big-frickin'-wow!
In the days when we were a powerful nation - the days when we were an Empire - having a monarch meant something, and made perfect sense. In today's world, there is surely no room or reason for them.
To all those in the rest of the World... What do you make of the British Royal Family? And Royals in general?