There's also an issue with camera UI that phones managed to largely bypass. I remember getting a Canon t4i with a touch screen. The touch interface was actually pretty decent and this was probably ~10 years ago! But a lot of "camera people" hated it. They'd complain that it would inevitably lead to smudges on the screen and they wanted physical controls instead.

So who do you sell a dedicated camera to? A new UI will largely alienate the small market that still exists. The old UI guarantees an unappealing product for the smartphone user.

Ultimately all interfaces have to be easily navigable with buttons and this has consequences.