Apple probably knew that even less market is there for the smallest size with pro features
Or maybe the 12 Mini isn't selling as expected because people actually want a Pro Mini - which isn't offered. This really is such a strange thought that it doesn't even occur to you?
Y'all say Apple knows what they're doing and has done their research. The company that proudly brought you the voice-controlled iPod nano, iTunes Ping, or the Newton.
Apple in the past was criticized for lack of choice in their product line
Choice is good. The current product line is beyond choice, though.
My husband spend an entire day on the weekend comparing the different models - most people don't go to that length and either buy the cheapest, the flagship (because 'the best') or what's thrown at them through their cell phone carriers (as someone else commented, and most of them default to the 12).
Have you even looked at ALL the currently available options for "iPhone"? There's FIVE different models (12 Pro, 12, SE, 11, XR), each with different sub-options for e.g. screen size, GB, etc.
For example, why have THREE options that I assume are supposed to be "budget options"? Great, offer choice of FaceID vs. TouchID. You still don't need two options for the basically same size (11 vs. XR).
Why have inconsistent sizes between the "Pro" and the "standard" "latest model" line? (12 vs. 12 Pro) It's purely marketing trying to get more money out of people and to be able to say that in theory they offer choice. It's not that they actually listened to people.
It's fragmented, inconsistent, and confusing. But if you always default to the Pro flagship of either size, you wouldn't realize this anyways because you didn't have to bother.