The thread is well structured and makes good points but the reality is, people aren't gonna read an entire book just to pick up quirks to add to their CP's. Additionally, playing every CP as a tyrant would make the whole concept bland, removing the actual variety amongst characters. The dialogue in half life 2 suggests that the reason people enlist is not monochrome, nor is their behavior. They either do what is required or go above and beyond to excel at being pieces of shit for their own personal pleasure or to rise up the ranks.
I do agree that there appear to be a lot of rather mellow cops at present, but from my experience someone hounding you 24/7 and shoving the fact 'I AM BEING TYRANNICAL AND ABUSING YOU BECAUSE WE ARE IN AN ALIEN DYSTOPIA' gets old really fucking quick and the fun to be had becomes one-sided for the one inflicting the IC tyranny, rather than one being subjected to it.
Point is, everything is good in moderation.