Is it reasonable to say the vast majority of people simply do not sit next to a charger with the headphones in, more than once a year? I'd think so. I've literally never done it myself.
I appreciate there are edge cases and that it's a tricky decision, but getting 5% of a phone's volume/thickness back for a port Further I think the majority of charge & listen usecases are those where dongles aren't horrible. (although they'll always suck). i.e., listening to music while charging in a car, is a specific use case where dropping $25-50 on a one-time solution is somewhat reasonable for the edgecase user who does that every single day. Same with a setup at work where you've got a headphone on and charge because you're a heavy user or forgot to plug it in before bedtime the night before. These are non-mobile situations in known/safe areas, where you can just leave the dongle. Which is a bit different from the dongle experience one has with say a Macbook which is charged during the day, on the go, in many different locations etc.
Despite the fact I think it makes sense for the majority, I'll grant it's still a shitty situation for the minority. But even then, I think the ubiquitous advent of wireless audio is around the corner. We've seen big gains in quality of connectivity, range, price level, battery, style and comfort. And we're now seeing some pretty unique innovations too like swiping your earbud to silence the room. I'm not a big fan yet, but I think it's a very decent extra solution to some of these issues.
Overal, I'm quite alright, even in favour to see the port get dropped, if it was usb-c all the way.