....for the iWatch to work you NEED an iPhone - but you also need to charge the iWatch EVERYday!
You need to charge an iPhone pretty much every day too, in most cases.
Also, the other smart watches need another device to work too. Android Wear needs Android devices. Pebble needs iOS or Android devices. Or are you stuck comparing a smart watch to a watch?! Which is like comparing using a phone to using telegrams....