Modern phones are all phablets and it sucks but it's the only format they offer. Smaller phones are nicer to hold and nicer to use for everyday tasks. My thumb can actually reach things. At least AI will no doubt reduce the need for pressing buttons.

Manufacturers want phones to be thin so the only way to fit in the battery life is for the whole phone to be larger. In case you didn't notice it's really really difficult to find a side on photo of the iPhone Duo closed. They don't want to show the thickness.