This is a good question. I personally think they should be upfront about how a particular software update will affect performance if it is significant. Folks don't need to know every little detail, but for something like the sudden shut off issue, Apple probably should have been upfront about it.But does a company have a responsibility to their customers to tell them they are making changes to the way their phone performs?
While I agree with you that most people don't understand the nuances of lithium batteries and such, I do think that pretty much everyone has a strong grasp on batteries in general. We have all been trained to understand that the more you use a battery, the shorter the usable duration will become. So eventually, a fully charged battery won't be able to power your device/toy/car/whatever for as long as it did when it was new.I would assume most people do not understand lithium battery technology, how the lifespan of the battery is limited, and the conditions which could lead to battery failure. I say it is up to the manufacturer to educate their customers. Tell them that as time goes on battery life diminishes, and what changes they are going to make to the way your phone performs in order to prolong the useful life of your phone and battery. Oh ya, or you could just replace the battery and continue using the phone as is.
The issue that Apple is facing is that over time, the batteries that Apple are using cannot maintain high enough current to prevent the iPhone from shutting down in some circumstances. As I've come to learn (from some forum members) is that all lithium batteries will exhibit a loss in current delivery as the battery ages with use. I don't think this is a widely understood phenomena amongst the general population.
So maybe Apple should have designed/specified batteries that can deliver higher current levels, commensurate with the required current levels of their CPUs/GPUs. I've said this before on other threads, but my belief is that around the time the 6S was released, I think Apple lowered the specs on their batteries. For the most part, the sudden shut-down bug was a 6S issue. So early builds of iPhone6 would have batteries from a good batch, but later ones would have batteries similar in build to the 6S, so that's why throttling affected the 6.
THEORY/HYPOTHESIS - my wife's iPhone6 doesn't exhibit any throttling and is over three years old (92% health). My iPhone6 lasted 2 years on the original battery before being able to hold a decent charge. Replaced the battery (OEM battery from Apple) in late 2016 and I was hit with an underperforming battery leading to throttling. My hope is that Apple learned enough about this battery issue and has begun to specify better batteries in their newer iPhones (and other devices) so as to prevent this from happening again.