WooHooMan
Auror
In story world, monarchies seem to offer the following: fancy dresses, a clear target, and ready-made politics.
I think a big point you’re missing is the romantic iconography associate with kingship.
When worldbuilding, it can be very convenient to have a single character that can act as a representation for, not just the government but the entire nation and its culture.
And for a story, it can be convenient to say that the character inherently must mold themselves into the king role. I mean, that’s what the Lion King is about and I’m sure the creators of that movie had absolutely no intention of delving into politics or history.