First of all, an iPhone not having a ¼" headphone jack does not mean you can't use your existing wired headphones. You'd just need to use the provided adapter. Of course there will be situations where you'll want to charge and listen to wired headphones at the same time, but that's also been taken care of with inductive charging, so that argument doesn't work as well anymore.
Second, wireless headphones have progressed significantly in the past couple of years. They're not what they used to be and can be better than some wired headphones. Is there more work to be done - of course, but that brings me to my third point.
Third, like so many things, it often takes a purposeful change away from the status quo in order to improve and move forward. And at these times of change, there will always be unhappy consumers not wanting to change and move forward, often for very good reasons, but not moving forward to satisfy some, ends up holding everyone else behind. I can name countless examples, from 45 records to 8 track tape, to cassette taps to CD's to DVD's to MP3's. Or tube televisions to LCD to OLED. Multi-pin computer connections to USB-A to USB-C. 8" floppy disk to 5.25" floppy disk to CD to DVD to USB drives. At some point each technology had millions of everyday users that ended up having to change in order to move ahead with something that was clearly better - even if it wasn't clear to everyone at the time it was happening.
In the case of very expensive wired studio-quality headphones, they're also unfortunately such a small segment of the overall market, that they effectively become meaningless for most manufacturers to chase after. It's much like the market for tube amplifiers / receivers and high end loudspeakers. There is definitely a market for both, but it's small and for a mass market company like Apple, or Samsung for that matter, they're just not going to jump in and try to serve that segment - offering a headphone jack on their smartphone is at this point more of a marketing ploy than anything else.
