My understanding of the change they made was that it was expressly to deal with a condition with failing batteries where, as they were nearing the end of their life, they would just shut off abruptly when they still claimed to have 40% or more charge left -- the problem was that they could no longer deliver peak power, and if the phone tried to draw what was now too much power for something, it'd fail. The solution to that was to limit how much power the phone could draw.
I don't think it was intentionally nefarious -- this is a real problem with this kind of battery and I've experienced it, and it's not unique to Apple devices. In theory, their solution is actually pretty good! The problem was the way they communicated this to end users, namely, that they didn't. They just did it. And didn't even have iOS tell you it had enabled this "battery management" mode when it was turned on.
This wasn't an engineering fiasco, it was a PR fiasco. Apple has always been guilty of what we could diplomatically call "under-communicating," but this is the sort of change someone -- many someones, arguably -- internally should have flagged and said, "No, look, this isn't something we should just do silently, in part because it's going to create a suboptimal user experience and in part because if we don't communicate what we're doing and why we're doing it, it's going to come across as us just slowing old phones down to make you buy new ones."
A short-lived consumable that can't be field-replaced is always an engineering fiasco. I used to keep a spare battery in my backpack; an external USB battery is not a reliable substitute when (not if) the internal battery gets bad enough.
I don't think it was intentionally nefarious -- this is a real problem with this kind of battery and I've experienced it, and it's not unique to Apple devices. In theory, their solution is actually pretty good! The problem was the way they communicated this to end users, namely, that they didn't. They just did it. And didn't even have iOS tell you it had enabled this "battery management" mode when it was turned on.
This wasn't an engineering fiasco, it was a PR fiasco. Apple has always been guilty of what we could diplomatically call "under-communicating," but this is the sort of change someone -- many someones, arguably -- internally should have flagged and said, "No, look, this isn't something we should just do silently, in part because it's going to create a suboptimal user experience and in part because if we don't communicate what we're doing and why we're doing it, it's going to come across as us just slowing old phones down to make you buy new ones."