Apple understands that Apple Watch, by its very nature, will be more personal than the iPhone. It’s not just in your pocket, separated and tucked away when not in use. A wrist based device is on you and out there all the time for everyone to see.
Not only that, but you are being asked to allow this device to know more about you than your doctor. To let it pay for things for you. To help you communicate with your friends and loved ones in potentially more meaningful ways. And, to interact with it potentially more than you currently do with your iPhone.
Apple understands this will be the most personal computer you will own.