Every Greek state is special, though. My approach is not that Eretria is super special but that every major Hellene state is special in some way, and Eretria is just special in its own way. Besides, being special and "oc" is part of the draw. I'm not here to write history, I'm here to write alternate history. Players just have a tendency to translate special to "best" and presume supremacy over the rest of the Mediterranean, when Eretria isn't actually the best in a lot of ways beyond just numbers. It isn't the best at women's rights in the Greek world, it isn't the best at culture, it's not the wealthiest, the largest, the most innovative in citizenship, the most technologically advanced if such a classification can exist, etc. Eretria isn't even politically special since its constitutional form is popular in much of the west. There are unique aspects because this is an ancient society simulator, and players should have some opportunity to alter their ancient society.
I don't have time to go into every single Hellene state and how it's special, but obviously those who rise above the rest have some kind of advantages. For all its "specialness", Eretria is still basically a Greek state. The idea of a single "Hellene" culture is a complete falsehood in this period anyway, since the connection was linguistic and different regions followed different Gods and different customs that could vary wildly, with only a few universal icons like worship of Zeus. Some aspects are also not really all that "special" in the sense that Eretria has a monopoly on them, like a better taxation system. That's not something Eretria Eskhata can just keep over its neighbors forever, and part of it is purely taxing the metics. If you gave all your metics citizenship tomorrow you'd lose a third of your tax revenue. Part of the impulse to presume superiority in speciality is just player egotism (in the neutral sense) which can translate into hubris, but I'm fine with that since it's in character anyway.
The only thing I feel is a bit much is the population growth, which I'm going to significantly reduce after this election cycle.
And yes, it wasn't evident in the early quest, because these are retroactive thoughts, though some aspects like Eretria's taxation is something that emerged later anyway.