What I find fascinating is that Apple's and [Android manufacturers]'s previous attempts at smaller phones aren't even worth maintaining after they assess sales.
In my mind, these companies are all so massive they can afford a little fragmentation for the obviously small market, with no meaningful impact to their sales numbers or profits.
On the iPhone minis, there's very obviously a market for them, but the market is so small compared to the market for "all iPhones" that it practically vanishes in comparison, which leads Apple to not bother. Is it really that expensive to maintain a more niche line for each generation?