If you want big sales, you need to either have a fad, or solve a problem. Smartphones fill in wasted time (of course, many people just waste still more time playing mind numbing games, but other read news or whatever) and reduce the clutter of things one has to carry about.
The smart watch needs to help solve the really nasty problem of credit/debit card security. Type price in watch, card to watch, card to POS terminal (one hopes eventually to go watch to POS terminal, but this then limits the card vendors you can use reliably), POS terminal verifies a secure transfer and price. If the watch is removed, then the passphrase has to be entered again to use the watch thus reducing the chances of simultaneous random theft of both authenticating objects.
Now those slimy bustard Russky crackers will have a harder time of it, stealing a one time payment record won't put food on the table.
Oh, you mean Tommy iCook's iWatch can't do this secure thing? Hmm. Thought he was up on what consumers needed... security Tommy. Not gimcrackery fad objects.