It's the convenience, for me anyway - why carry around multiple devices, when one can do the job.

For travel photography, I went from carrying around a Sony full frame, to a Fuji XT3, to hoping by iPhone 19-20 that I can sell all my bodies and lenses and just rely on the iPhone.

The Sony felt like a chore - from carrying around a big camera and lens, through to the editing and photo management. The Fuji was a breath of fresh air - a bit more compact, and the film sims allowed me to cut the editing process out. But there was still lugging around a camera, and then the photo transfer etc.

With mobile phones' improvements in photography, coupled with the endless opportunities for apps, I can't wait to rely on it as my sole camera.

What do you expect the iPhone 19/20 to have that the iPhone 17 doesn't?

The tradeoffs will fundamentally be the same. You're not getting a > 100mm^2 sensor (with the glass lens required to image on it) on the iPhone anytime soon (or anytime ever really, unless the form factor of the iPhone dramatically changes).