It's a new product category. Smartphones were derided as a frivolous product and an inevitable failure in the early 2000s. By 2005, they were a niche product that has a market, but will never actually see mass adoption. When MS introduced tablets in 2001, industry analysts laughed at their supposed looking for a solution to a problem that doesn't exit. Now they snicker at IoT and wearables. It doesn't matter, the Apple Watch may prove a success or a failure in the long run, but there is little doubt that computers will continue to miniaturize and diffuse into more and more areas. Apple is smart in jumping on the bandwagon, and if this product fails, they will try others.