My biggest problem with this is that I do not want to have yet another device that requires batteries and/or charging in order for it to function. Wired headphones powered through the audio cable are simple, don't quit working if their battery drain, don't require charging, and you can find them anywhere if you need a replacement.
I have... I don't even know. 20? 50? devices that need to be charged on a regular basis. I really don't want to charge anything besides my phone and my laptop. I don't want the ritual of taking 2 or 5 or 10 different things out of my bag at the end of the day, plugging them in, and then unplugging them and rewrapping the cables and putting them back into my bag. That is not "convenience" in my book.
There's also a small level of cognitive overhead involved with remembering which devices were charged when. We're not talking rocket science here but most of us are IMHO already in a constant state of distraction thanks to information overload, and I don't want more variables to think about.
