I think certain kinds of content just look better on a big screen ex: videos and images. Also, if you have a limited budget you are not buying both a phone and a tablet (for the bigger screen to consume content). Instead you could buy a phablet to do both. So trade off one handed use for your phone against the cost of a tablet and not having access to the tablet at times. That's the tradeoff from the consumer's standpoint. From Apple's standpoint, they would have to design a phablet that works wells and can be economically produced. So for example, if they want the same quality screen as the iPhone, would the screen have really low yield rates and would thus be uneconomical to produce? Are there issue with building a larger aluminium frame? Do they have higher priorities or different products that they want to create?
