5. It's a human body interface.
A smartwatch on a wrist that fails to provide ways to assess the wearer's physical condition is no better than a wrist-mounted smartphone. Being in constant contact with a human body presents an opportunity to collect physiological data and convey information, kinetically, thermally or electronically, once human-machine interfaces improve. It's an opportunity that shouldn't be wasted.

6. It includes a cellular radio, or at least Bluetooth LE.
Devices matter more when they can connect to a network without an intermediary. Accessory devices, those that depend on smartphones for network access, have their place, but they're far less interesting. Our radio band should also be able to communicate directly with other devices of its ilk, to exchange contact information automatically when two people wearing radio bands shake hands, for example.

7. It's programmable, but not necessarily for apps.
Our radio band will be much more useful if developers can create software and services for it. These services probably won't look like apps that run on mobile devices, like games. The absence of a screen would preclude that. Rather, the device's services should work like IFTTT and Unix cron jobs: They should act periodically or when certain conditions are met. They'd be closer to Google Glassware than traditional apps.

8. It supports a broad range of input forms.
Of course our radio band should accommodate audio input and output. But it really ought to respond to touch and movements, not to mention other sensor data, to trigger events and applications. Most modern smartphones support accelerometer input, but usually this input is handled within apps. A better approach, and one that's starting to become more common among app developers, is to tie the accelerometer to a specific app or function, so it can communicate with the app without requiring the device to be unlocked or the relevant app to be active.

9. It can be locked and it responds to being severed.
One reason to have a device bound to your wrist is to keep from losing it. Another reason is for personal protection. There are several obvious applications for a wrist-bound device that would work better if the device were difficult to remove (personal tracking, reporting from insecure areas or self-defense) and if it could transmit data (location images and audio) upon being cut or unlocked.

10. It's affordable.
The bill of materials for an iPhone 5 starts at about $200. The display screen accounts for about a quarter of that cost. At $99 or below, radio bands would shift from being occasional purchases by gadget addicts and metrics-obsessed athletes to mass-market tools for a broad set of uses. The Samsung Gear is just too much at $299.

Smartwatches need to evolve. The sooner we stop thinking about them as watches and start thinking about them as wearable computers, the more likely we are to find meaningful uses for them.