If you're just taking a normal amount of photos and videos then cloud syncing over wifi works well. The fast data transfer rates are going to be most useful to people recording 4K video, especially if using it for professional projects with more than short clips.

Maybe the most important feature allowed by the USB 3 speeds is that iPhone 15 Pro can record directly to an external drive, so you can plug that in to your editing machine and not worry about the phone's internal storage at all. But it's not something normal people are going to do.

It's anecdote, not data, but I don't know a single person who has used their USB cable plugged into their iPhone to transfer data in a very, very long time.

So it intuitively aligns with my personal life and career experience.

I've never used my iPhone cable for anything other than charging and debugging, and even the latter I mostly do over WiFi. I can't think of a single case of any of my family members plugging theirs into computers – to them the cable is a "charger". Using a phone in combination with a laptop/desktop is an incredibly niche use-case.

What makes you think any non-pro users do need data transfer capability?

I don’t want to speak for anyone else, but I very rarely copy data over lightning. I think I’ve only ever done it a couple of times over the past few years, to copy mp3s to my phone from my laptop (which I gather is rare in this age of streaming).

Everything else goes over Wi-Fi.

Would it be nice if the cable was faster? Yes. Would I pay more for it? Dubious.

What use cases do you know of that would make >450Mbps speeds noticeable? (And I mean actually noticeable, not "this movie will take few seconds less to copy") Backups are incremental. Data copies are usually used for a small subset of files. Any common hardware attachments need way less.

Not an iDevice use, but it is very rare that I've transferred anything over a cable to/from my phones in recent years and I'm pretty sure I can say the same is true for many of my friends & other contacts.

I could imagine some people do though, for transferring video or big pictures when on slow asychronous Internet at home and don't want to wait for everything to sync up to the cloud. I shovel stuff over local wireless via SFTP in such situations but that is not a man-on-the-street compatible solution.

Plugging your phone into anything is a security risk that deserves assessment.