Well, the correct way to decide is to create a testable hypothesis that differs in outcomes between taking care of aging batteries and planned obsolescence, and then test it.
Hypothesis: If they wanted to take care of batteries/battery life, the phone/tablet would resume running at full clock speed when plugged in and charging.
On the other hand, my 6, same purchase day, can barely survive a full day of light use, and requires additional charging throughout the day if I'm calling or texting much
https://news.ycombinator.com/item?id=15889519