[T]he earliest watches lacked a minute hand because of the need to pack so much technology in to power them and also to drive the “display.” This wasn’t a problem since the accuracy was so poor they drifted off accurate timekeeping by up to hours every day! Their tiny springs and inefficient clockwork also meant they didn’t store much power. Thus they needed winding very regularly—at first with a key, just like traditional grandfather clocks and whatnot, which is self-evidently inconvenient.
Great article about the history of watches and battery life, going back 500 years. It’s interesting to me that Apple is very much positioning their Apple Watch as a watch and not just a wearable.