for certain joysticks, the device template can be used to provide a ctrlr file for mame, or other emulators to do joystick mappings. This is critical to the plug and play aspect of the system.
I had to make one for my X-Arcade Tank-stick, because it is insanely custom (it appears as an HID keyboard, and requires a custom controller file to work with MAME).
-Thom