Missed this one and I was there Dick.
C over D is clearly " upside down " airspace because the risk is obviously higher where traffic gets closer together.
Nobody wanted Class D. It was stupidly introduced as a sop to try and shut you up. My recollection was that 'Give him something' was the Airservices' position. Influence!
We wouldn't have this argument about 'C over D' if it had all remained C, you weren't pandered do, and what worked was left alone.