I think it just adds friction (for measure, I feel audio jacks are pretty good)
So the real response is, "what's wrong with most companies to not provide the 3.5mm itself?"
It's good that xperia's doing this though. I think I still have phones which have 3.5mm itself so there isn't much to worry about. I think there are a lot of new phones which do offer it, I think both of my parents phones have support for 3.5mm by itself.
One of my iPhone SE's died an untimely death because of failure of the lightning port, so I'm strongly sympathetic.
I also am a hardcore 3.5mm headphone user. Wireless headphones are garbage.
I did get my mind changed on USB-C DACs by way of inductive charging. Using an USB-C DAC and still being able to inductively charge seems at least somewaht reasonable to me.
On the newest round of phones for my wife and me I've tried to make sure we're inductively charging >90% of the time.
Need to dig deeper into inductive charging as it seems to heat the battery more especially if the phone is in a case. So yet another tradeoff to consider.
Good thing is that if the port goes bad it can still be charged.
USB-C extension cables aren't allowed, but pass-through charging is allowed. I suspect a $7 cable from a Chinese amazon seller is not spec-compliant, but e.g. Belkin sells a spec-compliant "3.5mm Audio + USB-C Charge Adapter".
In my experience the connection is much easier to accidentally break through movement (e.g., walking) with a USB-C adapter than straight-through 3.5mm.
I really miss having a 3.5mm output on my phone...
Hidden inside of a USB-C to 3.5mm adapter is an entire DAC with a power amplifier for driving headphones. They're complex little things.
And like any other bit of active, plug-in electronics: They're not all the same.
Some of them are wonderful (Apple's adapter sounds great and don't cost much), but and some of them are terrible.
And there's compatibility issues. The combination of an Apple headphone adapter on an Android produces a volume control bug that prevents a person from turning it up even to normal line level output voltages that normal audio equipment expects.
And there's functional issues: Want to play some lossless audio in the car or low-latency audio on headphones, and charge your phone at the same time? Good luck with that! (Yeah, there's adapters that have USB C inputs for power, too. They're a mess. And I once popped one as soon as my phone negotiated a 12VDC USB PD mode instead of the 5VDC that the adapter must have been made for. (And no, wireless charging isn't a solution. It's a bandaid for the deliberately-inflicted footgun incident that brought us here to begin with.))
And it's complicated: For a "simple" audio output, we've got USB 2 with a signalling rate of 480Mbps and a power supply, when all we really want is 20Hz-20KHz analog audio with left, right, ground, and (optionally) microphone.
And then: It often doesn't work. When I plug the USB C headphone adapter I have into my car and go for a drive, it disconnects sometimes: I observe no physical change, but the device resets, the music stops, and the phone rudely presents a prompt asking me which voice assistant I'd like to use (the answer is, of course, "None" -- it's always "None", but it asks anyway). And then I get to figure out how to make it play music again, which presents either a safety issue or a time-suck issue while I stop somewhere to futz with it. (Oh, right. Did I mention that the electronics in these adapters also include support for control buttons? I guess I glossed over that.)
Forcing the use of USB C headphone adapters and their complexities represents a very Rube Goldberg-esque solution to the simple problem of audio interconnection that had already been completely solved for as long as any of us reading this here have been alive.
Except: While Rube Goldberg contraptions are usually at least entertaining, this is just inelegant and disdainful.
If you’re in the low percent running cabled headphones, you probably are also running a headphone amp if necessary or not which uses more cell phone power.
Now you need a usb->usb + 3.5mm to keep it charged up or an add on battery.
but the real response is "what's wrong with a usb-c to 3.5mm adapter"