It's a "regular maintenance" type thing - less common than an oil change, sure, but perhaps just as necessary. So why not make it as easy as an oil change?
Having done both, I can tell you that replacing the battery on an iPhone is already easier than an oil change on a typical car. The iPhone parts are expensive, but it's a relatively simple operation for a trained person.
Not to mention that an Apple battery replacement is about the same cost as having someone change the oil in your car if you use full synthetic. I just don't get the complaints. If the battery is dying, get a new one. If you don't want to spend the money, then Apple has provided a feature that lets your phone keep running.
Not to mention there are an infinite number of 5 minute tutorials on YouTube. You don't have to be trained, you just need a set of eyes and a brain. I'm glad an increasing number of phone manufacturers, not just Apple, put form factor and durability above user laziness.
Cars, you may have noticed, are big. Apple has made a tradeoff between replaceable batteries and small phones, and the market has more or less agreed with this decision.
One of the reasons I upgraded to an iPhone X was that my 6 Plus was getting slow. I'm just now finding out that I could have replaced the battery for $85. Am I mad!?
No, I'm not. 3 years is long enough for a smart phone, I probably would have replaced it anyways. And I like the X way more.
My guess is most people plan to replace their phones after 2 years, and few have this problem before that. So disclosing probably doesn't change more than a minute number of purchase decisions. Though I don't doubt that some marketing person at Apple influenced limiting disclosure of this fix because they thought it helped upgrade rates. If that person exists, they should be fired, because it damaged Apple's credibility.
Instead of a hard to find value in settings that tells you your battery needs replacement, they should have a one time warning when it's first detected that explains this behavior.
Thank you for the your very informative message. I think messages like yours are somewhat lacking in this discussion.
I understand your argument. I think I would be somewhat mad, or maybe it's better to say, disappointed. While I most likely would have bought a new phone anyway, I would despise that Apple took away my ability to make this call. It also means that I could not refurbish the phone and pass it on to parents/friends.
In the last years, I am somewhat disillusioned by Apple. Instead of engineering a better overall package, the innovations seem to be based on cheats (I would the /undisclosed/ cpu down-clocking as such), cutting corners in QC and questionable design decisions (touchbar - why not with some touch feedback? No headphone jack for reasons already disproved by android phones.)
I didn't buy in into the ios eco-system, but like the mbp and mac os. But the number of advantages get smaller, and the number of disadvantages grows.
I mostly agree although I don't really know if my iPhone 6 seemingly getting slower is due to power throttling or general software optimized for more performance over time. The geekbench numbers are still fine. I'd hesitate to get a new battery purely on speculation my phone would get faster. So it would be nice if there were some indication of where the battery is in its life. Though like you, I'm upgrading to an X in any case.