For one, it makes their sensor suite equal to what mobile phones have. The IMU can be used alongside the camera for visual-inertial mapping and navigation, the

For one, it makes their sensor suite equal to what mobile phones have. The IMU can be used alongside the camera for visual-inertial mapping and navigation, the barometer could be used for localization across floors of a building (yes the barometers in a phone are good enough to pick up on a couple meters' pressure difference), the IMU can also be used for shake-related gestures e.g. ignoring sporadic mouse movements when you're using a laptop in a car, they can be used for gestures e.g. slapping the laptop left and right to switch virtual workspaces, ...