Exactly, I have an original SE and my wife a 13 mini and they work just fine. Why? Because she has a current laptop, I have two current laptops, I also have an current iMac, we share a pro Nikon camera, and we share a current iPad. To some people a phone is just a phone, period.
Now, I understand teenagers that can't or don't have multiple devices, but that does not mean that is the whole market. I also understand tech junkies that have to have the latest tech or it is just not worth going to the bar with friends. But again that is not the total market.
Her sister and husband also have an SE and a mini 13 and do just fine. In their case they also have two large iPads.
I think Apple is missing the fact that people that buy small phones probably spend more on iPads, laptops, and iMacs than people that don't.
So the mini size factor is a supplement to other Apple devices not a standalone sales category.
Everyone that I know that has bigger phablets, lament that they wish they could get the tech in a smaller form.
Apple does not really understand the relationship between size and tech, or they let their profit hoarding cloud their eyes. IIRC Jobs stated that the original phones were all the same tech, but different sizes. I think that is the right approach regardless of Jobs changing his mind later on when BOD and Wall Street starting hounding Apple for more profits.