I agree with you in theory, but I would guess 1) the market and 2) hardware constraints have led Apple to their current "Pro = large" philosophy. Basically... Professionals may be more likely (on average, not across the board) to want a larger canvas to work with, and packing in more power and features requires larger space and batteries, which naturally lends to getting bigger devices on that end of the spectrum.
All that is to say, I think there are valid reasons against a 12 Pro Mini. However, I completely agree that there should be a 12 Max (non-pro). Lots of market for it (older folks with bad eyesight, casual gamers/artists, binge streamers, etc.) that aren't going to care about RAM or stainless steel or dolby vision frame rates or whatever.
I have no doubt the market for the models I suggested are smaller than the market for the models they do produce, and might even be trivial for Apple. But I would very very happily take on that part of the business if Apple don't want it, and I'm sure I'd make enough to be retired in a matter of weeks or months. And even if it is chicken feed for Apple, it's about creating great products for the customers.
Talking about pros, well I am a professional software developer, and I need the portability of a laptop, but it doesn't have to be super light, and I want the biggest screen I can get (I used to use a 17" MBP back when they existed). But modern processors are all super computers these days, and I'm not doing any graphics processing, and the software I write doesn't have any massive compile times, so the bottom spec processor and graphics option of a MBA is well and truely enough for me. I do however run a lot of large software packages simultaneously, and although none of them need much cpu power, they do soak up a decent chunk of RAM and SSD. So for me, I need a big screen, largish RAM (16GB suffices at present, but 32GB is only around the corner, and 8GB is not enough), largish SSD (1TB is barely enough, 2TB+ would be needed soon), basic processor and graphics. Do see my point - I'm a pro, but I don't have the needs that Apple tries to shoehorn me into (which costs a damn huge amount). And I'm a pretty typical software dev, and there are a hell of a lot of us that use MacBooks, and a damn lot of us would be very happy with a 16" MBA with bigger RAM and SSD options (which don't take up any extra physical space, Apple simply hasn't made the options available, and you can't self upgrade after purchase anymore (don't get me started on that!!!)). Currently, the only choice I have that Apple sells right now is a 16" MBP, and because I can't upgrade the RAM and SSD after I've bought it, I would either put 16GB/1TB in it, knowing that I'll have to upgrade soon and have to sell it and buy a new one; or put 32GB/2TB in it. Both options are incredibly expensive. So for now, I happily sit on my 2015 15" rMBP with 16GB and 1TB (which I have already upgraded, and could well upgrade again to 2TB before I buy a new laptop), and wait for Apple to make something that has the specs I need, but doesn't massively and unfairly eat into my snowboarding budget (oh, and doesn't have weird flaws, but I'm not holding my breath on that one). The reality is, I will probably use this laptop until it dies, begrudgingly buy a new overpriced machine, hold onto it for 7 or 8 years, and repeat.
