Oddly enough, just yesterday I downloaded coconutBattery to check out the state of my three year old iPad Pro's battery. It's probably going to need a replacement in the next year or so, I estimate. (~83%)Yet people keep buying
So, I looked at what a new iPad Pro would bring me. And the cost.
I'm sure the newer models are faster and in some ways cooler, but ~$1300 versus $99 for a new battery ended that thought trail very quickly.
However, in general I think you're right. Many people are just itchy for the newest thing. Human nature, I suspect, along with subtle persuasion from Apple and the media. There should probably be a statue of Edward Bernays somewhere on Apple's campus.