Tim Cook's answer to my first question

Tim Cook was asked the first question (on the iPhone portfolio). His answer is paraphrased here:

We haven’t so far. That doesn’t shut off the future. Why? It takes a lot of really hard work to do a phone right when you manage the hardware and software and services in it. We’ve chosen to put our energy on doing that right. We haven’t been focused on working multiple lines.

Think about the evolution of the iPod over time. The shuffle didn’t have the same functionality as other products. It was a really good product, but it played a different role — it was great for some customers it was strikingly different than other iPods. The mini played a different role than the classic did. If you remember when we brought out the mini people said we’d never sell any. It was too expensive and had too little storage. The mini proved that people want something lighter, thinner, smaller. My only point is that these products all served a different person, a different type, a different need. For the phone that is the question. Are we now at a point that we need to do that?

…

At a macro level, a large screen today comes with a lot of tradeoffs. When you look at the size, but they also look at things like do the photos show the proper color? The white balance, the reflectivity, battery life. The longevity of the display. There are a bunch of things that are very important. What our customers want is for us to weigh those and come out with a decision. At this point we think the Retina display is the best. In a hypothetical world where those tradeoffs didn’t exist, you could see a bigger screen as a differentiator.

Full interview here, answer begins around minute 37.

Here is how I interpret the answer:

• The iPhone portfolio may still arrive. It hasn’t so far because the cost/benefit is not there for Apple. On one hand it would take a great deal more sourcing effort and risk while dealing with constraints in production. On the other it would not not offer meaningful additions to the customer base. At least so far. The economics and the demand may change (or have changed) and the time will come for a broader portfolio.
• The comparison to iPod is not entirely appropriate because as a music player, the iPod had a relatively small set of jobs to do. It was hired for exercise, escapism, isolation, etc. It was not hired for apps and services which extend the medium itself. In other words it was not a computer. As a computer, the iPhone has a near infinite set of jobs to be done and it’s the hundreds of thousands of apps which help it perform them. But as a result the iPhone needs to conform to the dynamics of ecosystems and that means consistency of APIs and user experience. It cannot vary in terms of input methods, or be below minimum requirements of screen size or memory and power.
• Because of the rapidly expanding job space, Apple believes the iPhone was not “good enough” for all these years. The improvements shipped for each generation were all “meaningful” in that they were valuable and absorbable. Users would use the new features (like better screens, cameras, battery, etc.) and they were willing to pay for them (as evidenced by the sustained high average price).
• On the question of what the extension might be, changing screen size is one dimension but it has to be balanced by performance gains that don’t detract from other dimensions. Engineering is all about compromise and consumers pay Apple to make these compromises in an intelligent way. Apple does not come to an answer to the question of balance by launching many products and seeing what works. It cannot afford to dilute its brand with a long list of failures. Other brands may not be affected by trial-and-error approaches to the market but they are discounted by the customer accordingly.