You don't have your lifecycle set to the generation length -- phones, as you note, are around 2-3 years, but they have a lifecycle of one year. The fact that the watch has a much worse lifecycle than the phone -- despite being half the cost -- gives valuable insight into Apple's beliefs about how compelling it is.

If the Apple Watch were amazing, and a new generation could be more amazing yet, why wouldn't a substantial number of the owners upgrade in a year?