I'll speak mostly from my experience here, on what I have had the occasion to witness for the 4 factions over the years.
- The Amarr have always suffered from the villain trope, thanks mostly to the slavery aspect, which literally detonates when coupled with religion. I am not sure they have been ever once portrayed as the good guys in the minds of players. Even maybe in some chronicles where they were truly compared in a good light with the Federation (like in 2 Deaths). Not to help them further, they have often looked like utter fools on the intergalactic scene, but they are far from being alone in that. But incidentally enough the Amarr had enough of charisma to still appeal to strong core groups of RPers, that eventually vanished the last years. It was a slow and painful decline.
- The Caldari, when I started and up until Heth, have always seemed obviously good and the favorite of many people, including maybe CCP, to my eyes. It was not a hazard that 40% of players were Caldari, even with the Achura and their insane attribute distribution. They sure were portrayed their flaws, but eventually they suffered from the same syndrome than the Minmatar, which is the victim syndrome where for the reason evoked by Etienne, they were often considered not as perfectly good guys, but an ideal worthy of respect and adoration for most. They always looked strong, meritocratic, militarist, and well, everything that made all of us geeks wet inside. Then TEA happened, harming the faction in a bad way, and meritocracy was the only thing that players were able to clench onto by default because everything else was collapsing around them. And eventually the recent events were they were kicked in Luminaire, which is one of the first time I witness a major defeat in Caldari history tbh. In any case, they sure have suffered from the wrong reasons, and have lost a lot of their immaculate status.
- The Minmatar have always been the favored race to be considered the good guys in my experience, until recently. The madmax/rebel look, freedom loving dudes flying in rusty ships with style, fighting against oppressors and tyranny, had a lot of success in all those years for RPers. But the few past years, they have lost a lot of their appeal to RPers it seems. Not sure why, until Colelie, which was a major blow.
- The Gallente have always suffered of a mixed portrayal. The fact that they have never really witnessed a strong core group of loyalists (the curse of federal diversity) put aside, they have always represented 2 antagonist things closely related to our modern world : the western ideals, naturally held by most of us players as our christian/western legacy, like liberty, democracy, etc, which could have probably have been even stronger than the minmatar appeal to a lot of players initially, but also all the flaws of our current society, and especially now with the economic crisis, were we are confronted to corruption, and all the cons we tend to despise IRL, now. And the latter easily get projected on the Gallente Federation (with good reasons), but eventually become personal pets peeve for a lot of players that for the same reason than the Amarr on who players can unleash their hatred of religion/slavery, they can be spitted on for the things we hate IRL, were they suddenly become twisted corrupted bloated entities. Also, the Gallente have also suffered from an interest part of the PF, where they up until the battle of CP, were literally apathetic vegetables, suffering and taking hits and never doing anything against that. That, alone, I think hurt the faction a lot more than the rest since its very loyalists started to get "meh" about the loss of charisma projected by their faction over the years (like for the Amarr).
For humans being atrociously good at adaption I think any of New Eden's models are realistic and would work. After all we're collectively in for a dystopic future, unless we can overcome fickle things like free will and egoism. (Hello Sansha). To play devil's advocate, Lyn, I think that all the (empire, for the sake of simplicity) systems in New Eden are good models of society, because none of them are highly dysfunctional or objectively evil to their own subjects, nor to humankind in its entirety. Today's advanced societies enjoy their warring as much as them, as the exploitations of weaker nations. We're not just very good at adaption, we're also pretty good at self-defeception, after all.
But for the sake of this discussion I think I know what you mean, and I would tend to agree. People who do not see both sides of the(ir) factions OOCly are very tedious to deal with.
Of course they can be good/valid models of society.