It's true that it's a walled garden. But with everything the device has access to, cameras pointed at your pupils, cameras pointed at your surroundings, precise tracking of where you look (which the OS prevents apps from accessing), I'm not sure I want apps to have full permission to the hardware. The more "intimate" devices become, the less you can trust random apps. They still let you run whatever you want on your own device as a dev, which seems like a good compromise. But I'd never trust other people's apps with access to all that.
