I agree.. The dedicated space alone saves me a significant amount of time carting equipment from basement to garage and back. Space and finances have not always allowed me to have this, but man, it's nice.
There's also a habit part.. There were not AIO systems when I started brewing, and I've spent years slowly upgrading my keggle based system. So I'm comfortable with it, I know what to expect, and I enjoy the process. It's good for me to have time to relax, listen to some music, and do my thing. If it were simplified to push a button, I don't think I would get the down-time as I would attempt to do other stuff while I brew.