It is a class, you can use it right now like any other. It just does nothing different from a worker.
I don’t believe a ruler of any kind (king, commander, mayor, etc) is beneficial to the game. No need for a hearthling to give orders around when I can do that through the game interface. Walking around buffing people is also suggested a lot and also not something that would make a difference to the game, and when it does, it is redundant as it can be achieved through other means.
This is purely a role play class. You can for example recreate yourself in game and be promoted to a king to show that you are above others. You can have two queens happy in a mansion. Or 4 kings in a castle, like in Narnia.