Smartphone builders had similarly vague ideas about which problem they were solving: they knew they needed to give access to some dumbed-down subset of the web and of our computer data. They knew that mails were part of that subset. Mail is easy, it's SMS with a different transport protocol, right? So they were looking for a dumbed-down keyboard, dumbed-down mouse, dumbed-down windows, scrollbars, etc.
The iPhone took a mile-high view of the problem. "Dumbed-down mice (stylus) and keyboards suck. How do we make them superfluous? And how do we get adequate access to non-dumbed-down Internet, too?"
Now with the watch. We have some vague fragments too. We know when we don't want to take our phone out, so in each of those cases we plan to use the watch as a dumbed-down phone screen. It's probably touch-sensitive, too (in a dumbed-down way no doubt), and it lets you awkwardly have a subset of the interactions you'd have had with your phone. So, I bet that watch is nothing but a dumbed-down proxy of our phone.
I'm still waiting for someone, not unlikely Apple, to show me what I really wanted from a smart watch, without realizing it. And if apple figured this out as well as they figured out the smartphone, the Google-wearable guys will kick themselves during the demo, the way the Android guys decomposed themselves while Jobs was showing them what they should have done.