I ditched my iPhone because of the lack of something this basic, I'm glad I bought an iPad mini last year while they still have this functionality.
N.B. (1) I can't use in-ear ear-buds (2) I have high quality wired headphones I want to use (3) I want to use it in my car which although it has bluetooth, does not work with music, only with phone calls
"our devices are so thin and light..."
no shit, half of the device is outside, you just have to carry this bag of dongles with you
Very frequently, I use my wired headphones and charge the device at the same time.
I'm glad I can do that without some dodgy external dongle.
A headphone jack is pennies. I don’t want to buy, possibly charge and generally carry around something else when this is a solved problem that Apple has broken.
I also like being able to charge my device AND listen to it at the same time.