What made smartphones useful was people discovered new uses that you just couldn't use a computer for. You can't do turn-by-turn navigation with your laptop in the car. It's nearly useless if you're standing at a street corner in an unfamiliar city and want to know where the closest coffeeshop with wifi is. You can't use it to take a picture of the cute little ducks crossing the road and send it to your wife. It does you no good when you want to hail a car to take you home.
People haven't yet discovered similar uses for a smartwatch. It's highly likely that they exist, though. What the watch gives you is hands-free information: you can receive quick, 1-5 second notifications even if you're carrying something or immersed (sometimes literally) in physical activity. I've already found this useful for getting notifications that my founders' group has changed where we're meeting while I'm driving there, or that my wife has already gone to the grocery store, or for checking off items on my shopping list while carrying shopping bags. There are probably other bigger uses waiting to be discovered.