Well your right. If all your wanting to do is have your w580 (which is just our lazy way of writing w580i, and if it ended in 'c' it just implies its for china) to have all the aditional features and a lot less of those "junk" files as you called them, you just need to debrand it. If for any reason in the future you decided to switch phone carriers to someone else, then you would need to unlock it in order to be able to use your w580 with the other carrier. For the debranding you can follow this guide to flash a new firmware onto your phone. Just make sure you use a GENERIC_MAIN and you can go here to get an idea of what languages each FS contains, just make sure that the MAIN and the FS are the same firmware version.