But the optimization can in turn "come at the expense of older devices which may not be optimized for the most recent operating system, or vice versa," said Nguyen. "The situation becomes increasingly thorny because operating systems and hardware are becoming increasingly complex and can have unintended consequences that weren't caught in quality control testing."
Even so, Apple "prides itself on the user experience, which is a significant part of its brand value, and building its products around this end-goal. I think this is why they're being called out so vocally on it."
Avi Greengart, a mobile analyst with GlobalData, said the fact that batteries degrade over time in all devices is "a consequence of chemistry, not a secret plot by Apple to get consumers to buy new phones."
He said he accepts the company's argument that Phones with older batteries needed the adjustment to prevent them from resetting and causing more issues for users.
Greengart agrees the company could have done a better job explaining it all to iPhone owners without springing it on them unannounced.
"There is actually a fairly straightforward fix that solves the reset problem without slowing performance: replace your phone's battery when it gets old," he advised. "While the iPhone is not user-serviceable, Apple charges $79 for battery replacements – a tiny fraction of the cost of a new phone. If you're paying for AppleCare, you really have no excuse—a new battery is free."
Greengart said he is skeptical of complaints by some critics who allege that the company made the changes as part of a planned obsolescence scheme.
"[That's] just hard to swallow when it comes to Apple," he said. "This is the company that sells old phones for years longer than rivals and keeps those phones updated with the latest software."
Another analyst, Rob Enderle of Enderle Research, is more skeptical and said he's not completely buying Apple's explanation.
"Apple is attempting to get us to believe they are throttling down the processor because, by doing so, it helps keep the iPhone battery from dying prematurely rather than the more likely reason that they want folks with older iPhones to grow unhappy with them and buy new ones," he said.
"The problem with their argument is that you can deploy technology that will revitalize Lithium-ion batteries and they haven't, and you can design phones where the battery is easily replaceable, and they haven't [done that either]."
Instead of the company's carefully-crafted explanation, Enderle said "the more likely cause of this screwy policy is that Apple wants to ensure iPhone churn, in other words force an upgrade cycle." That's largely because the phones aren't necessarily packed with enough revolutionary features each year to drive upgrade cycles, he said.
He said it is "a typical behavior of a company that lives on a lock in strategy—it believes the customers can't change vendors, so it comes up with creative ways to mine their customers for money. IBM did something like this in the 1980s and discovered that customers, even locked in customers, will revolt if they become aware they are being mined for money."
For Apple, "this policy doesn't bode well long term for the company or its customers," said Enderle.