It's getting harder and harder to justify swapping out your phone every two years. The phone industry relied on this pattern for a decade and made a killing thanks to rapidly iterating tech and carrier subsidies that hid real prices.
But now the prices are out there, front and center. They're high! And instead of revolutionary new features, we mostly get steady improvements of existing ones.
Perhaps more importantly, our phones just hold up better now, too. There's no reason to buy a brand-new $750 (or more!) phone when your two-year-old version is just a little bit sluggish. You'll get a nicer design, sure. But for that amount of money, you can probably hold onto what you have just a little bit longer.