These are the people who are annoyed by no headphone jack...
1. Musical purists. Where wired will sound better than bluetooth, but... you can still use the lightning port and it sounds great but you need a dongle.
2. Stingy people.
3. Perfectly fine headphone owners. People who own great headphones and don't see why they have to give them up.
4. People who want to charge and listen at the same time.
5. People who just like to complain.
6. People who think a dongle is a PITA.
I'm in the other camp. I think the sound quality is now good enough on Bluetooth for the vast majority of users and BT headphones are cheap enough that if you can afford an iPhone, you can afford a set of BT headphones.
The day I went wireless via the airpods with my iphone was truly liberating. I'm not joking when I say that it was massive in terms of changing the ease of use of my phone both at work and on the go. Those god damn cables used to constantly get in the way.
In saying that, I still used wired for my computer, because I'm not moving around and for Keynote or Video editing there is absolutely no lag at all and no chance of cutting out suddenly. I would like to dump them though for the sake of less clutter on my desk.