Agreed on iPhone versions not feeling significant. I personally consider it a good thing. I'll keep my phone for as long as possible and not feel the need to upgrade.
I personally don't care if Siri is the worst LLM of the big players, as long as it can answer my basic questions and search my texts, I'm happy. I don't need "frontier intelligence" for that kind of stuff.
As for dictation, they say the new dictation is much better, requiring an iPhone 17. Unfortunately, I won't get to find out if that's true for another five or so years, but I'm hopeful for a better dictation on device, because you're right.