IO
You are quite right and I only mentioned it as I thought you said:
Power = torque x RPM
I did qualify by mentioning my pedantic mood.
I also agree with your points regarding outputs, although modern ECUs can achieve an economy that we cannot achieve with the same safety margin.
A modern ECU will be adjusting for optimum lean thousands of times a second, dependant on all factors (temps, fuel quality, air density ec). We can get it about right, but either we aren't as close as we could be or we are into the danger zone of predetonation.
The modern diesel engine is the perfect example of this. Diesels ten years ago were awful. Now they are the engine of choice, in everything except racing. Its the engine management that has dramatically changed, not the mechanical parts.