Fantasy lit and its obsession with the monarchy

Think about it.

It's always the princes... always the princesses... the kings, the queens.

Is there a reason why fantasy literature so often revolves around medieval politics, and stretches them into a more stereotypical extent where the fair maiden is always the daughter of a royal house, and is all perfect and everything, and the hero always tries to win her heart? Or the fact that the prince is always so... princely? I mean, you rarely see a "Squire Charming" or a bold knight who fights for the heart of a peasant girl...

And even LOTR isn't free of this.

So, why does royalty play such a great role in fantasy?