Moonphase (& many other complications) are there not because they are required in a daily basis. They are there simply because they can. The truth is, tourbillon is in fact a yesterday solution to a near obsolete problems. In the last century, pocket watches are so inaccurate as it sit idle in the same position in the pocket for so long, and there arises the innovation to overcome the problem. It was novelty, brilliant & set apart the noble from the peasant. Today thou, watches changes position as we move our hand, and even a Seiko 5 can keep time within few seconds a day. But that doesn't stop JLC for making Gyrotourbillon, Greubel Forsey to squeeze four tourbillons into a watch. They do it because they can, thanks to technology & know-how over the years. Same story with Sidereal time, Moonphase, and allow me to say, even chronograph. And minute repeater, nobody owning one today will need it out of necessity. I don't think many people use tachymeter or regatta either. Correct me if I'm wrong. So the only reason watch connoisseurs wear watches with these complications is because of the appreciation on the mechanical excellency, the man's ingenuity & perseverance, the superiority of owning fine things and the fascination of the inner curiosity.
