Gizmodo asks why Apple (maybe) wants to make a new iPhone with a 5″ screen. The problem seems to be that most open-format systems have a dozen combinations of screen size, aspect ratio, total resolution, device capability etc, and all of this complexity gives developers fits. Apple has (for the most part) one screen ratio and a small but growing number of options for total resolution. This makes it much easier to write an app that will work on the broadest number of devices.
For example, to simplify compatibility the iPad mini has the exact same pixel number and screen ratio of the iPad 2, it just compresses them into a smaller space. Even so the mini has pixels that are rather too large, at about 160 pixels per inch, to qualify for Apple’s 260-ish ‘retina’ hi-res standard. On a lark I jotted some numbers down and figured that if Apple made a ‘retina’ device with the same total pixels and aspect ratio as the iPad2/mini, it would measure about five inches diagonal. Voila, you have a brand new device in a new niche for which developers don’t have to write a single line of code. Within reason of course; some apps with little buttons would need a very pointy styulus. A smart move on Apple’s part IMO. However, I would caution that micro-niching makes it more and more likely that someone will walk into an Apple store, get overwhelmed with the options and leave.