A few days ago David Pogue wrote that if the next iPhone is indeed bigger and comes with a 4-inch screen, it could be out of necessity due to LTE:

I’m guessing that the iPhone’s upsizing will be equally necessary to accommodate a bigger battery, so that Apple can solve the 4G/dead battery issue.

Meaning: We all know that LTE chips drain cell phone batteries → thus the iPhone needs a higher-capacity battery → thus the iPhone needs to be physically bigger → thus, why not slap on a bigger screen while you’re at it?

There are two assumptions about this premise that I don’t like: (1) that Apple won’t find a way to implement LTE without also putting a significantly larger battery into the iPhone; and (2) that Apple would allow LTE implementation to dictate significant hardware design changes, especially changes that affect the screen.

The first may be true, but the second I just don’t see happening.

If we take the new iPad as an example of a Retina display device with LTE, we see that the LTE chip Apple is using in the iPad is nothing compared to the screen’s drain on the battery. Matthew Panzarino wrote in March:

LTE on the new iPad accounts for roughly 10% of the battery’s capacity. The rest of the increase can be attributed to the more powerful processor, screen and bump in RAM. This is remarkable on its own, because its far less than most 4G phones require, indicating that Apple has worked with Qualcomm to intensely tweak the chip for power consumption.

Did you know that if you use the new iPad as an LTE hotspot with the display turned off, the battery will last over 25 hours? As AnandTech pointed out in their iPad 3 review: “If you want to use the new iPad as a personal hotspot, you’ll likely run out of data before you run out of battery life.”

Today’s iPhone already has a battery strong enough to power its Retina screen. And though the next iPhone may indeed have a larger screen, a higher-capacity battery, and LTE connectivity. Assuming that happens, we may never know if LTE forced a bigger phone, or if a bigger phone allowed for LTE. Apple will never say which new component was the “most important” component to the hardware design team. But actually, we do know: it’s the display. It’s always been the display and always will be.

• Apple, at its heart, is a software company. And, using some text from my iPad 3 review, the other side of the coin to iOS is the Retina display. Meaning, iOS is the software and the screen is the hardware and that’s pretty much it. That is the device. It’s a screen that becomes whatever pixels are lit up underneath.

On a laptop you have three user interface components: the keyboard, the trackpad, and the display where you watch the user interface. On the iPad and iPhone you have one user interface: the screen. And you touch and manipulate and interact with what you see on that screen.

I love the way Ryan Block explained why the new iPad’s Retina display was such a big deal:

The core experience of the iPad, and every tablet for that matter, is the screen. It’s so fundamental that it’s almost completely forgettable. Post-PC devices have absolutely nothing to hide behind. Specs, form-factors, all that stuff melts away in favor of something else that’s much more intangible. When the software provides the metaphor for the device, every tablet lives and dies by the display and what’s on that display.

Ever since 2007, one of the hallmark engineering feats of iOS has been its responsiveness to touch input. When you’re using an iOS app it feels as if you are actually moving the pixels underneath your finger. If that responsiveness matters at all, if iOS matters at all, then so does the quality and realism of the screen itself. The display is the central hardware component.

• Secondly, of the millions of iPhones that Apple will sell all around the globe, how many will be to people who live in an LTE city? The new iPad’s LTE chip works only with carriers in the US and Canada. There are LTE bands all around the globe that the iPad does not support. While it’s possible the next iPhone will be more versatile in its LTE offerings, and thus be available on more 4G bands than just USA and Canada, it’s no guarantee.

Looking at LTE coverage just in the United States, AT&T has 39 LTE-equipped markets which cover 79 million people (or 23% of the US population), and Verizon has 258 markets covering 200 million people (or 65% of the US population).

My point being: 100-percent of iPhone 5 buyers will use the iPhone by holding it in their hand, touching the screen, and plugging it in to charge. But, for one reason or another, less than 100-percent will be able to connect to an LTE network.

The iPhone’s display is its preeminent hardware feature — everything else is secondary. If the next iPhone has a bigger display it will be because Apple decided bigger is better. As awesome as LTE is, it isn’t awesome enough to be the feature which dictates significant hardware changes to the iPhone.