How is it “physical waste”? No one is forcing you to buy a new phone and in the case of iPhones, Apple has released security updates in the past year for all iPhones introduced in the last decade.
I have an iPhone 12 Pro Max that is three generations behind now. While there is nothing I have to have, the always on display, the USB 3 speed, and video out to my portable USB-C monitor on the iPhone 15 Pro would be nice.