Although you can map any participating device commands to an activity, they eventually clutter the activity(ies). The sound and picture buttons (on some models) provide a direct short cut to the 2 mostly used devices. Although you can achieve the same thing in device mode, editing their button mapping is a real pain compared to that of the sound and picture mode. Unlike the device mode, which comes pre-mapped with the entire device command dataset, the simple default mapping for the sound and picture mode, which is very similar to that of the activity, makes editing a lot easier.