I agree, and I absolutely think that Apple should allow downgrading, just like they have on macOS for literal decades.
I remember moving my 2009 MacBook from Sierra to lion before I sold it, and the performance difference was ridiculous. The thing could barely run Sierra, but absolutely flew through lion.
Of course, it was probably all down to the 2 GB of ram the machine had, but still.
Although I do have to give them credit, it has gotten a lot better. My 12 mini, which originally shipped with iOS 14, ran iOS 17 just fine, as does the iPhone 11.
I don’t really know anything about the battery stats between the operating systems though, it may have gotten slightly worse.
My mini had awful battery life, even on its original version
To Apple’s credit, performance has gotten a lot better. Yes, slowdowns and keyboard lag both occur, but unlike before (back in the 32-bit era, and even early 64-bit), devices are a lot better when fully updated.
Battery life got better but solely due to sheer size, and only recently. The original battery life has been so good that even though updates severely worsen it, they’re still at least kind of usable.
However, and in spite the aforementioned improvements, updates still severely decrease performance and battery life, if updated far enough, and when compared to the original iOS version.
The iPhone Xʀ on iOS 17 is nowhere near iOS 12 in terms of battery life, and performance has suffered, too. A9 devices are very poor on both counts when fully updated as well.
An updated iPhone 6s with a kind of degraded battery would be perfect on iOS 10 (say, 85%), and it’s unusable on iOS 15, probably getting a couple of hours of screen-on time at most.
An iPhone Xʀ on iOS 17 probably gets around 6-7 hours, whereas it gets twice that on iOS 12. So, the difference when comparing an updated 6s and an updated Xʀ is apparent, yet that does not mean that the Xʀ is perfect. It’s usable, and that’s as far as my praise goes. Also, like I said, small - and annoying - slight instances of lag and glitches are ubiquitous. Keyboard lag, slowdowns which may not be severe enough to disrupt operations, but they’re severe enough for users to notice.
I am absolutely sure that users on iOS 17 would be pleasantly surprised should they be able to revert back to iOS 12, on both counts: performance, and battery life.
For that reason, which includes the fact that Apple just can’t help themselves but degrade the experience every time, even if it’s better than it used to be, Apple should allow downgrading at any time for any reason. They are wrong and at fault for not allowing that.
Like I said earlier, we can do one thing to fight this: never update.
This is what I do, and my experience with iOS devices is excellent:
https://forums.macrumors.com/thread...wing-down-older-iphones.2413230/post-32783229