When we look at the PP scenario and the ''2power s" that are the only one that is believable, to some ectent is the Pirate Lord...
He is a viscious SOB and he does not hide it and it is totally in line with lore.... but!!!:
The emergence of such "power" would lore wise compel the Feds and Imps to get rid of him, you know he is bad for business, so he has to go, and they would get rid of him, eventually...
With raw power and might.
As for the other "powers" , to make them believeable it should have been , much more about sublety, secret missions, trading indermining, "hidden" Embargoes, smuggeling and such stuff..
Behind the scenes work, not this semi open warfare...
The different "powers" should have offered a true believable moral compass to follow, a little Like Antal, but they should stick to them and not just allow missions blowing up peacefull people or opponents in the open, in secret yes..
An opponent should not show up as "hostile" , rubbish, you scan them and their allegiance is revealed, but that does not automatically make them a legitimate target

...
Each "power " should have a rallying cause, which is set witin the majors powers policies :
Example Winters mission could have been to abolish slavery completely in the galaxy, Patreus could have vied for the return of "godd ol " Empire values, and the Alliance guy would have as target winning the minds of the Independents, and opposing the Imps and Feds in secret....
Most missions should be rather shady, with all deniability, of course "open war" could happen in a secluded place where 2 "power" suddenly were at heads, but this should be a fast thing , not static, as all the other powers meddle , including the Majors, to stop this "insanity"...
The combat between the powers would be much like a short term "CG" lasting for a couple of days and the outcome should be measured and put into the game..
The "merit system" is gross and stupid and not needed, you simply rank up within your "power" as we are used to, use decay if you want, and are rewarded in credits.
The upkeep of systems system, which actually is believe-able , is ok as it makes sense...
Its odd , in this day and age that FD never understood that most Cmdr's in this game are in for a ride, not primarely having 'Condas and multiple billion credits, you can do that.... but WHY ?..
This game is , and has always been about becoming Elite, if they had added a moral perspective to it too, it would have been good.
For c. 's sake look a forums : some Cmdr's swear to kill all slave traders, some swear to stay Independent, some long for ye olde days, some are psychoes that want to burn and kill, some are ect...
Had PP been more in line with above scant thoughts, I could/would have embraced PP as believe-able and immersion giving, and could 'prolly have found a place to fit in and align to and support.
Cheers Cmdr's