Given that a watch is just always on your wrist it’s easier to carry when going for a run or into a store, while still allowing you to listen to music and receive calls. It also makes it less disruptive to look at notifications. And the payments work without any further authentication as long as the watch remains on your wrist, without fail (at least in my experience), whereas Apple Pay on the phone will ask for the phone passcode every now and then.
Given that a watch is just always on your wrist it’s easier to carry when going for a run or into a store, while still allowing you to listen to music and receive calls. It also makes it less disruptive to look at notifications. And the payments work without any further authentication as long as the watch remains on your wrist, without fail (at least in my experience), whereas Apple Pay on the phone will ask for the phone passcode every now and then.