72 Dart Swinger 3.6L Pentastar +T5

So why do we need to vary the pressure? I understand the engineers did this to optimize the engine for every day driving but can it just be locked out somehow to an ideal pressure?

I know nothing but … for what its worth, regarding "variable oil pressure", I bumped into this snippet of info on the Mikuni company web site in a totally unrelated search regarding something else. It may to some extent answer your question.

Automobiles | Products Information | MIKUNI corporation
Variable Valve Timing System (VVT&OCV)
Hydraulic actuator to control cam shaft phase for the engine. Solenoid valve to control oil pressure to be applied to VVT.