If I’m buying a phone 4 years into the cycle, I don’t want to start with a 4-year-old CPU and camera. 5 years later, when I’m ready to get a new phone, that’ll be a 9-year-old CPU and camera. I’d rather have the latest tech when I buy it, and use it until it stops working.
I agree though that the physical design should stay the same, so that cases and accessories don’t need to be thrown away. Apple more-or-less does this with the iPhones, eg a case should work with any iPhone 12-14.