boss in nether

In the Overworld there is the Warden and in the end there is the Ender Dragon but in the Nether there is nothing. There should be a temple that naturally spawns near the fortresses that is an open room with the wither set up and the only missing block is the middle wither skeleton skull head and when you put it there the wither spawns and you fight it. This way it is an optional boss and it is an easier way to get a nether star and you don't have to go looking for wither skeleton skulls.