When I lived in NYC (or traveled back to Silicon Valley), I kinda expected to see them everywhere (and did). But unintuitively, I also see them all the time in places I'd never expect (like say seeing a half dozen people wearing them in a Wal-mart in rural Arkansas). Yes, I'm looking for people wearing them so obviously I'll see them more, but that doesn't negate my point that I see more Apple Watches than any other brand of watch (smart or otherwise).
On the other hand, sports watches that track GPS and heart rate etc, do something that you don't want to use your phone for. (I have a Garmin that is fantastic.)
Smart watches will take off when people nail the use case, and don't forget that we already have phones, so the watch doesn't need to do everything.
Because I just don't need it. I get only a dozen emails and whatsapp messages a day, I might spent at max an hour per week talking on the phone and my current schedule is very simple (e.g. wake up in the morning and drive to work).
There is just no way how a smart watch could improve my day.
I can see some usecases if you are a very busy person with a crammed schedule but for normal person there is just no need to have one.
There's also that the watch (traditional or smart) is not so traditional to wear anymore anyway. Most people just don't bother owing one.