In economics, economies of scale are cost advantages that certain enterprises have. Up to a certain point, there are increasing benefits as more output is yielded. However, at most of these economies has a limit point, or sweet spot, at which point each additional unit starts to cost more and more. Keeping this in mind, it seems like we may be soon approaching this point when it comes to screen resolution.
The differences between a Full HD screen (Xperia Z on left at 1920 x 1080 pixels) and a HD Display (1280 x 720 pixels on right) /