Earlier quoted context omitted.
Smaller screened smartphones aren't a new market that needs to be defined though. Most people know what they are by virtue of having lived through the era that they were the only choice. And as OP pointed out, Apple makes a smaller screened smartphone, so they exist. In some comment on this post someone said that it accounts for 3% of Apple's phone sales. How big is the group of people that want a smaller smart phone…
I suspect there are two constraints working against mini mobiles: 1. The industry push for thin due to the consumer dislike of thick. 2. The invisible consumer expectation that smaller mobiles should be cheaper. A mini screen with a fat body (large battery, good camera) is what many functionally oriented people should want, but cost and form will limit consumer desire and make it an extremely niche product?!? Edit: I…
* Lower performance due to small battery and poorer heat dissipation
* No physical space to put top-tier camera