The problem with wearables is that they are by definition battery dependent. And if they're not low-powered enough to run for years on a battery like a traditional watch is, then the issue is going to be how useful are they vs. how much of a pain is it to remember to plug it in every day.
I have two 7" Android tablets, and I never use either of them. Sure, for some of the stuff they can do, they do it better than my Android phone. But the phone is the thing that goes on the charger every night. And for all the niceness of the bigger screen, I can't be bothered to keep the tablets charged. There's also the issue of the tablets not supporting separate user accounts, so where they might be useful as a household device for reading email, etc, I won't put my email account on it without separate lockscreen passwords. I suppose I could buy yet another tablet to get one that runs Jelly Bean, with multi-user accounts - but seriously... I'd upgrade the current ones in a minute, but the OEM won't provide an upgrade or allow it to be unlocked so I can install Cyanogenmod. So, I'll never buy another on some faith that that one would actually be used. I suppose iPad fans might chime in with how much use they get out of their pads, but I see all of the same problems there - except the upgrades, but iPads aren't multiuser either.
So, essentially, the only thing I ever used my tablets for was to watch Netflix streams - and then I got a Bluray player with Netflix built in. Netflix has moved to the TV - Big screen, no charging. I suppose I might charge a tablet up to take on a trip for reading the NYTimes online, but seriously...