In all seriousness, despite the smart phone trying to be the "singular essential, do everything device", I don't think it does a great job at doing that, simply because it does too many things and has that addictive quality (ironically, I'm tyoung this message on my currently charging phone).
I like redundancy, I like not being tied to my phone and being shit out of luck when it doesn't work. I like how my watch doesn't need to be charged every night or how it looks unprofessional when I use it for a time reference, in my notes at work. Like
@FacePunch said, I like associating my watches with experiences and stories. Phones depreciate and are disposable; your future grandkids won't be fighting over who inherits your iPhone X.