The iPhone 4S is officially upon us, and, overall, the handset is leaps and bounds better than anything else on the market. However, for all its accolades and technical merit, Apple’s newest flagship represents a most curious critical paradox. You see, despite its record-breaking sales and unprecedented demand, the iPhone 4S is easily Apple’s most publicly lamented (and outright decried!) product of the last ten years.

Why?

It’s simple, really: The iPhone 4S is not the reinvented model everyone expected. To those having eagerly anticipated a world-changing 2011 upgrade from Apple R&D, the Cupertino company has done nearly nothing to alter the external design and functional size of its previously-released, 16-month-old iPhone 4. The 4S has the same aluminum-banded glass design, the same “scrawny” 3.5-inch screen, and — for all intents and purposes — the same feel and cachet of last year’s old news.

As a leading Apple and iOS blog, we at AppAdvice shoulder some of the responsibility for pushing the premature promise of a bigger, thinner, sleeker new iPhone. We weren’t initially convinced, though, predicting the handset would be an iterative, spec-bumped release rather than something completely new. We even supported the “4S” moniker! But, after the historical launch window came and went — after months of delays and rumors and leaks — it seemed almost certain Apple’d be unveiling a brand new form factor in tandem with its forecasted iCloud service.

The entire industry was convinced.

And the entire industry was let down.

The primary complaint voiced the world over was Apple’s failure to increase the iPhone’s small IPS display. After all, most contemporary smartphones boast screens at least half an inch larger than the familiar iPhone standard, and users have been calling for a size increase for what seems like forever. Last year, Apple calmed that clamor with the iPhone 4′s high-resolution Retina upgrade, but it’s safe to say the screen’s limited size desperately needs to grow. And larger, too — not just longer (in the tooth).

Naturally, though, it’s not that simple. Apple decided against increasing the iPhone’s dimensions for a number of logical (and logistical) reasons, and it’s important for us — as fans and savvy tech-heads alike — to understand precisely why Apple chose this “unpopular” strategy.

Many websites around the internet are actively positing the “ergonomics” angle, explaining that the iPhone’s 3.5-inch screen exemplifies the so-called “sweet spot” for easy utility and full, one-handed system control. Even John Gruber says so! Truly, the point deserves more than some little merit; and — from a user-experience point of view — it’s explained quite plainly by the following image:

Average user screen coverage comparison.

As Gizmodo’s Jesus Diaz summarizes, the graphic

makes total sense. And that is exactly why we would never see any larger screen iPhone. That 3.5-inch screen will be the ideal size until all humans are 7-feet tall and have hands the size of frying pans.

While we can realistically replace Diaz’ “would never” with “won’t until next year,” the argument is sound.

But that’s not the holdup.

Nor is iPad ratio parity or ease of development any real concern for Apple’s inevitable march of progress. These points all seem valid, and they are — to a degree. But, in a complex world of internal and external intricacies, such concepts are but the proverbial tip of the iceberg. They are, ultimately, mere superficialities. And beauty, it is said, is only skin-deep.

The real reason Apple’s decided to maintain the status quo — at least for a while — is firmly embedded in the age-old concept of supply and demand. Apple’s mobiles are without question the most sought-after pieces of consumer kit anywhere on Earth. It is hardly a surprise, then, that the company would choose to meet that overwhelming demand instead of neglecting it to bottleneck its entire manufactory output with some radically different product.

Consider: Apple is expected to sell over 100 million iPhones in 2012. That’s an absolutely astronomical number, and it’s one that’s taken Apple a very long time to approach with confidence and efficiency. To meet this projection (or, really, to even come close), Apple must rely on its already-established assembly-line processes. Each new design brings with it tremendous factory change, costly construction and installation fees, worker training and product orientation, and general output slowdown. Every time Apple redesigns its iPhone, it incurs billions of dollars in setup expenses and loses money each day it doesn’t clear its sale backlogs. Remember waiting three months for Best Buy to get reliable iPad 2 stock? How about AT&T and Verizon telling you, week after week, to “call back tomorrow”? Well, add another 160 million customers to the mix (via Sprint and China Telecom), and it’s even more obvious why Apple had to build its new handset on the iPhone 4′s existing platform.

On paper, we should’ve known better. All of us.

Duh. We can say that now.

Sure, we want Apple to give us the next big thing at each announcement and product launch. We love being wowed by Jony Ive’s cool new designs and Apple’s impeccable stylistic know-how. But things don’t always work that way. And things can’t work that way every single year.

The original iPhone launched in 2007. A year later, the iPhone 3G was released. The 3G brought a large aesthetic change, but the shape and overall form-factor closely mimicked its forebear. Another year later came the 3GS, and it was, again, nearly identical to the 3G physically. 2010′s iPhone 4 heralded the first major external change for the iPhone line, replacing three years of general sameness. Yet now, just 16 months later, folks are actually complaining about the 4S’ looks. Crazy!

Perhaps without that extra four months of limbo past the iPhone’s expected refresh, we’d be singing Siri a different tune. But the delay was necessary: iOS 5 and iCloud weren’t ready, and Apple meant to maintain its track record of rolling out a new version of its mobile OS with each new model that made it to market.

In our industry, we rarely get quality and quantity together — It’s usually one or the other. Somehow, though, Apple gives us both. It just takes a little bit longer. I, for one, am fine with that.

And, as far as I’m concerned, the iPhone 4S is off the hook.

But the iPhone 5 will be off the chain!