Apple's such a slave to the thickness that they put a smaller battery on the high end 13" than they do in the base model.
I think you're missing the point. People want the option for 32GB even if it increases power consumption. Given how most people don't need more than 16GB, you can probably assume that those pining for 32GB are at least willing to make that compromise.
I'm sticking to my 2015 MBPr until the next refresh. That refresh should be based on Intel Kaby Lake and the 200 chipset. This at least technically will allow Apple to offert 32 GByte memory versions.
Seriously. They do not care about RAM as Pro users clearly do and we feel betrayed. I wonder if and when will anti-touch display stubbornness vanish as it kind of did when they introduced stylus (sorry, Pencil).
If you wanted to add 32G in a laptop, then DDR4 and reduced battery life are your only options.
A good example is the XPS 15, which trades battery life for DDR4.
Design within the limitations and handling market requirements in short.
XPS 15 uses DDR4, is even thinner if possible than the MBP and has less than 4 hours of battery.
IMO MBP should be performance focused, being battery life a secondary concern, while keeping MBA as an ultrabook.
Each one to their own devices, so to speak.