It's really not that hard to understand the move to larger phones, but I think it was more about competitor's necessity than lack of diligence on Apple's part.
Cellphones always varied in size, but generally they were built as small as their basic user interface elements (screens and keyboards) constrained them to be. It was generally about portability.
When touch-enabled smartphones emerged, the keyboard dissappeared, but they were still sized as small as they realistically could be, as users still needed a realistic target size for input, and a functional display area within the limits of average human vision.
Following the iPhone's success, competitors in the space that Apple had basically invented had great difficulty differentiating themselves. They went through multiple iterations with only limited success. Price, which had traditionally led the market, didn't seem to get traction, and producing an equivalent product for a lower price seemed very difficult against Apple's hard-won efficiences of scale. This dilemma left OEMs to root around amongst the remaining vectors at hand.
And so we saw Samsung, and then others, make smartphone screens larger. And with larger screen sizes came more internal case volume - and so larger batteries and therefore longer battery life came along for the ride. They now had a toehold in "different".
Meanwhile Apple introduced the iPad - and content creators and app designers created even richer and more visually interesting mobile experiences. Consumers soon got into the habit of consuming more and more visually rich content on the go or in casual settings. The new form factor opened more market doors.
Samsung and others launched products into this market, and once again found limited success. They tried the same form factor, then smaller and smaller versions in order to lower costs in the belief that price conscious consumers would eventually choose them. They didn't. It's unclear whether this was because their operating systems were immature or app selection limited, but time and again Apple's products won over first world consumers.
Eventually the smartphone market matured but Samsung's incredible iteration machine was still adding dozens of permutations - including the 5.3" Note in 2011. The term "phablet" entered the market. Like the netbook, the tech press identified it as a new hybrid category and sales followed.
With maturation came market saturation. Samsung migrated the majority of it's cellphone business to smartphones that addressed lower and lower priced markets looking for growth. While emerging markets never really embraced the pricey second screen of 10" tablets, they were connected to the same internet as the rest of the world, and found that the phablet category offered them what they wanted in a single device.
Now Apple appears on the verge of entering this market. It will be interesting to see how they "differentiate" themselves on Samsung's turf. |