I believe it's not as complicated.
The Air and the Pro series are different in a number of ways, beyond the RAM and CPU configurations, as has been mentioned numerous times.. display, speakers, thermals, etc. etc. and both have their advantages.
Bottom line is if you already know you need a certain amount of RAM or a certain level of processing / graphics performance then you are smart enough to compare the two different types of laptop Apple offers specced the way you want / need, see how much they cost and then just decide on one.
It's actually much easier compared to choosing a Windows laptop, isn't it? It's just Air or Pro, one or the other.
The older Air had better performance relative to the Pros than the current Airs do. The original intention was for the low-spec MBP to be the replacement Air (they said this at the announcement back in 2016), the MacBook to be the basic computer for everybody. But that didn't take because people were too attached to the old Airs... so Apple shifted and put the MacBook CPU into the new MacBook Air. While the standard Ultrabook cpu continues to be in the low end Pro.
To me the old Airs were good performers for the time. The current Air doesn't seem as good to me compared to what else is out there, it's just adequate. That might align better with what the 'perception' of an Air is and what a Pro is. But I see no reason why Apple needs to stick with the low wattage CPU in a laptop that's as large as the current Air is. Well I see the reason... but it does nothing for me as a consumer...