I'm not a millenial and have "gotten over it", but that doesn't mean I have to like it. For example, a few weeks ago my BT earphones ran out of battery while listening to an audiobook in the middle of a transcontinental flight, and of course the 2.5mm adapter was unreachable in my checked bag. If my iPhone had a headphone jack, I simply could have asked a flight attendant for a pair of those cheap airline earbuds. I also had numerous occasions where I only had my BT earphones due to being an iPhone 8 user, but wanted to plug in to something with a headphone jack (e.g. an inflight entertainment system or a colleague's laptop) and of course didn't have cabled earphones. I guess because of Apple's "courage" I'm now supposed to carry two pairs of earphones plus adapters at all times?
The thing is that the 2.5mm jack is still ubiquitous, no matter what Apple does. It was just completely unnecessary to take away this option. Dropping all USB-A ports on the latest Macbook Pros was a similarly stupid decision. After 1.5 years, USB-C is still exotic for computers and USB-A is still ubiquitous. I can't count the number of occasions where someone gave me a USB stick and I was unable to read it because I didn't have the stupid adapter with me.