I think the average Romulan has more freedom than the average Cardassian ever did (during their military government period anyway).
I think they have a considerable amount of freedom and it's possible that their "Senate" represents a truly representative democracy. The fact that they are aggressive and xenophobic towards outsiders doesn't indicate anything about their internal politics.
The thing I'm curious about
: if Vulcanoids have dysfunctionally strong emotions which threatens their social stability; and Vulcans have coped with this by making a fetish of emotional repression; and Romulans are Vulcans who have rejected this solution; then how do Romulans cope? Is
the xenophobia their coping mechanism?
Also, why precisely did Romulans reject Surak's solution? Has that ever been explained? Is it simply that it represented a rejection of the true nature of Vulcanoids? If so, I think there's a good argument for the Romulans being right, at least in an abstract philosophical sense, but not so much in a pragmatic sense.
Vulcans have been far more successful in dealing with other species precisely because they reject their true natures. Everyone gets on the Vulcans' case for being prickly jerks, but they've actually made a considerable sacrifice simply for the benefit of interstellar relations.
The Romulans see a "manifest destiny" to one day rule the galaxy.
Do they? I haven't noticed truly imperialistic tendencies - they don't continually strive for conquest, but instead have a pattern of getting into fights and then retreating for long periods of time.
To me, this suggests that the fighting is an extension of their coping mechanism. Rather than direct their dysfunctional emotions inward, and threaten their ability to have a functional society, they turn it outwards.
In that sense, their aggressiveness is parallel to Klingons', which also is not inherently imperialistic, but rather just an expression of their culture. Ironically, Klingons are in a better position to turn their warlike ways on and off, as appropriate to a given situation. They aren't hostage to their aggression, like Romulans are.
The most truly imperialistic entities in the Star Trek
cosmos are the Federation and the Dominion. Those are both societies that seem determined to expand continuously, for the sake of expansion.