One pitfall of the wearables world is that you can't always be sure before you buy a device that every single feature will be available when you hook the thing up to your phone. Sometimes iOS owners get a better deal than Android owners, sometimes it's the other way around.
And Windows 10 phone fans? Good luck.
In an ideal world we'd like to see a near-identical experience across all platforms, which would probably require the device to be doing a fair bit of the grunt work itself, rather than being at the mercy of how the phone's operating systems work.
The good news is that new wearable-grade CPUs will make wearables more intelligent, without making them massive. The Intel Curie chip is the 'size of a button', while the Cortex-M series is improving at a speed which full-size mobile phone CPUs can only look back on wistfully.