This opinion piece sums up precisely why Smartwatches are a fad idea: a smartwatch simply cannot have most of the things on the author's list simply because it's a watch! 2 inch screen at a maximum. How do you propose to reply to content with that? How do you propose to read an entire article on 2 inches? Full navigable UI? If the success of a smartwatch is reliant on these things, then the smartwatch is a fad simply because it cannot have these things.
The smartwatch needs to be totally rethought as a concept. Why replicate smartphone functionality? 99% of the time it's really not an issue to just grab your phone out of your pocket, and I sincerely doubt that for that remaining 1% any notification will be life or death - and if it is you'll have already factored it in. Or is our always-connected, smartphone generation so totally hooked into their digital lives they must access torrents of useless information as fast as possible, and the 2 seconds saved raising their wrist over grabbing their phone is somehow a boon?
If that IS the case then just use Google Glass so your Facebook notifications can be sent directly to your eyes without any interaction from you.
I agree completely with Lephuronn above. The only useful wrist-based 'smart' device will be something like the devices you see in sci-fi films - something that is a small candy bar size, laying lengthways along your wrist. It's screen would be big enough to show a decent amount of text, and its battery will be large enough to last for at least a week of always-on usage. The Apple watch, and others, remain pointless.