If you've seen the pics of the purported next-generation iPhone built from allegedly leaked parts, you probably noticed it looks a whole lot like the iPhone 4/4S. While this may seem to poke at the persistent rumors of a Steve-overseen overhaul of the 5-year-old handset, the idea that Apple needed to ditch its glass-and-metal enclosure to transform the iPhone was always a bit farfetched.

Think about it. The MacBook Pro with Retina Display, possibly the greatest laptop ever made--and certainly the best to ever come out of Cupertino's labs--is a ground-up redesign of the MacBook Pro, but the external differences are fairly subtle; only when placed side by side are the new ports and thinner body obvious. Yet using it still feels like a whole new experience.

There was a time when Apple would have blown the doors off with the Retina MacBook, when it felt the need to make every new model starkly different from its predecessor: Power Mac cases sported mirror drive doors; iBooks changed colors and shapes; iMacs gained flexible necks. These aesthetic changes wasn’t always necessary, but they kept people interested in Apple products (even if they weren’t buying them).

Simply put, Apple needed to make a splash with each new product just to get noticed. It doesn’t have that problem anymore.

Now, Apple doesn’t need to rush back to the drawing board so quickly. The iMac hasn’t changed its form since 2007, and the Power Mac G5 has had its cheese-grater enclosure for the better part of a decade. Even the iPad hasn’t really changed its look all that much since it was introduced two years ago, yet each model is instantly distinguishable from the prior.

With the iPhone, Apple has taken a slightly different tack. The original stands alone with its aluminum backing, but the next two polycarbonate models, the 3G and 3GS, retained a similar shape. It wasn't until the fourth generation when Apple completely scrapped the old design. However, the Leica-inspired design wasn't new for the sake of being new; a retina screen and front-facing camera likely necessitated the need for a redesign, as did scattered customer complaints about overheating and battery life issues.

Antennagate aside, Apple hit the sweet sport with the iPhone 4. It's still one of the best designed phones on the market, and its industrial design is unmistakable. Where the iPhone 3GS was fairly pedestrian as a flagship handset (especially by the time it was replaced), the iPhone 4 is still as sleek and sexy as it ever was. Much like the iMac--which also graduated from polycarbonate to aluminum before adopting a unibody shell, much like the iPhone prototype--its design shows few if any signs of age.

With or without a radical new design, we know the iPhone is going to fly off shelves. But more importantly, Apple's learned that it doesn't need to force the process. It's what's inside that counts.