Same reason Acura stopped making small cars like the Integra/RSX: costs scale more slowly than revenue as car size increases, so selling to the small car market segment results in unearned potential profits — even if the small car segment is a majority, it’s better to make a higher profit per unit on fewer unit sales if your most primary goal is to min/max labor/profit.

(Small phones, unlike small cars, also have costs in UI development to maintain their form factor’s OS support, which can create an additional pressure to withhold devices for a viable and profitable market.)