[noggin]

My TV remote already controls the AVR volume without having to do nothing but using the ARC port.

Yes - but not all TVs have ARC. I'm running a c.2008 Sony 40W4000 as my secondary display - very nice LCD with proper 24p support (minimal picture-mangling digital processing - no Motion Flow etc.) - but it doesn't have ARC.

Also - if I have to switch from my Kodi remote solution to my TV remote to change the volume of my AVR then I may was well pick up the AVR remote. Some of us ONLY use CEC for remote AVR volume control from Kodi as we use smartphone remotes OR alternative input solutions like little RF keyboards, or favourite IR remotes with more keys than our TVs have for CEC remote control (personally I love the TivoSlide Pro and the Sony PS 3 Blu-ray BD remotes for Kodi). I find using my TV remote to control Kodi over CEC quite limiting so don't use CEC for that! (Not enough short cut keys)