I think that’s a trap — a way to be fooled by your eyes. [...] But it was the 3GS that first improved on CPU performance and gave us the first improvements to the camera. The 4S ushered in Siri integration and a much faster camera. The 5S was Apple’s first 64-bit ARM device, years ahead of the competition, and was the first device with Touch ID. For a typical iPhone user on a two-year upgrade cycle, I think the S years are the better phones, historically.
Iteration and refinement are at the core of great product development. A never ending feedback loop with customers that builds the foundation of the best products. "S" cycles are perceived as minor upgrades because of the same look, but I could not disagree more. Despite the most transformative features of the iPhone have been sponsored by S models, Gruber's points on the underlying thesis behind the S cycles are really well thought.
- Ecosystem: cases and accessories manufacturers count on this predictability and it makes their business more sustainable.
- Branding: never thought of it, but it's absolutely true. iPhone is more than a phone, it is an iconic device. Keeping its design consistent and recognizable is the most powerful force Apple has in order to retain this awareness.
- Predictability: manufacturing at "iPhone scale" is almost an engineering and operations wonder. Having laid out the industrial design two years ahead makes it easier for engineering to plan for the new releases.