I don't think there's anything "environmentally friendly" about making users have an extra dongle to get basic functionality.
My personal use case for the headphone jack is playing music in my car. My car doesn't even have an aux input (I have to use a cassette adapter), let alone Bluetooth. And when I'm on a long drive, being able to play music while charging is a must. I will only very rarely hook up a pair of wired earbuds to my phone, but I absolutely must have a headphone jack.
I wish I had the same problem as you do with your car. Mine is old enough that it doesn't have Bluetooth (I'm not the first owner and Bluetooth was an "extra" in this model) but new enough that there is no cassette player (and no built-in aux input) :)