Also, the tasks we're accomplishing on our phones have not fundamentally changed over the past five years. (The five years before that, sure, but things have slowed down.) If my phone is performing the same actions as when I bought it, why should I have to buy a new one to get security updates? If nothing else, it's clearly bad for the planet.
And, for that matter—and this is where iPhones do miss the mark—why does my phone not perform those actions as well as it did when new? That we have even faster chips nowadays shouldn't make the old ones slower.
Indeed. People like me care when a new phone has 20% more performance because that might mean the difference between being able to emulate a particular game console or not. I can't see why anyone else would care.
Rather it's because it can't supply the same voltage it could when it was new necessitating down-clocking of the CPU and thus the performance slowdown.
I've just bought an iPhone 6S second hand with a new battery. I don't know how fast they used to be, but I've not noticed anything being slow. Animations are silky smooth, and app loading times seem fast too.
I'm also on a 6S and Apple has kept it quite speedy! But, I was playing with a 2016 iPhone SE on iOS 9 about a year ago, and I could instantly tell it was snappier than my 6S on iOS 12.
The iPhone SE had the same CPU, GPU and RAM as the 6S but had far fewer pixels to deal with. That was probably more of a contributor to the snappiness than the iOS version.
In the iOS world, not generally so. Things generally get faster and more optimized (cruft gets removed) in the iOS world (barring some anomalies like iOS 13, but it's gotten back on track).
iOS 7, 11, and 13 are definitely slower than their respective immediate predecessors. iOS 9 and 12 are definitely the opposite.
But while it's hard to prove definitively—largely because highly-out-of-date iOS devices are so rare in the wild—I would posit that even though 12 was faster than 11, 9 and 10 were both faster than 12. That's definitely what I saw in a brief iOS 9 experience I mentioned elsewhere in this thread.
It's the old frog-in-boiling-water analogy. If it happens slowly, you don't notice.
A store in my city (in The Netherlands) replaces an 6S battery for EUR. 39 (US$ 44). They offer a 1 year guarantee. You can do some grocery shopping while they replace it.
Negative. The battery on my iPhone 6 was awesome and that phone was slow as molasses. Just switching to a family member's 6S was a dramatic improvement.
Only because I'm involved in this today and have apparently decided to not work on other things while I wait to go to the doctor:
6 -> 6S was a 450MHz clock speed (1.4GHz -> 1.85GHz) jump and doubled the RAM from 1GB to 2GB. That's a significant step up in capabilities. You probably noticed snappier application starts and transitions (more RAM, more apps can stay up at a time, or at least part of them so they start or seem to start faster) and better general performance (that 32% clock speed jump).
I wouldn't object to Apple (or anyone else) charging a reasonable fee for security updates past a certain date. (Where "reasonable" ≠ what Microsoft is charging businesses for Windows 7 support, for instance.)
Making people buy new hardware they don't need just to stay secure isn't merely wasting their money, it's actively harmful to the planet.
I wouldn't expect it to become a cash cow, no, but then neither does continuing to support the iPhone 6S. I do think they could more than break even, and that ought to be enough.
Moreover, companies ought to continue offering security updates because it's the right thing thing to do—for their customers, for their brand, and for the planet.
Possibly, but I believe this would be interpreted as a regressive tax - charging users with less money more than those with more money for the same software. Maybe it's fair if you consider QA and additional developers, but this is what the public reception would be.
And, for that matter—and this is where iPhones do miss the mark—why does my phone not perform those actions as well as it did when new? That we have even faster chips nowadays shouldn't make the old ones slower.