The monarchy these days to the running of the country is meaningless.
I tried to think of an american equivalent and I think I've got it. It's like the Prom King and Queen you see in the movies. They've nothing to do with the running of the system (school) but are a symbol of a lot that's wrong with it.
It's been that way since parliament fought a revolution and chopped Charles II's head off. In part for levying of taxes without representation & parliamentary consent...
In all fairness it does at least stop us having a powerful executive branch. I think it's much harder for a Prime Minister than a President to become a de facto king.