I dunno, the idea that the Romulans subjugated and tortured one of their own racial subcaste into mutant psychics, perhaps even having put all of their psychics into slavery and that's why they lost the ability, is a pretty notable element of empires as well.
Maybe, but oppressiveness is an aspect of empires that
Star Trek has shown routinely. Also, some empires are more oppressive and cruel than others, but the one thing they all have in common,
literally by definition, is that one state rules over multiple others and employs their resources and labor. I'm not talking in terms of moral judgments, but simply in terms of political science and the textbook definition of an empire as distinct from other political entities. And that fundamental defining feature of an empire is something Trek hardly ever shows in its alien "empires," with the exception of the one that wasn't even called an empire, namely the Dominion. (And the Son'a, but that was only in one movie.) So it was refreshing to see it established as an aspect of the Romulan Empire.
Beyond that, I'm sick of the laziness of Trek and other sci-fi in treating biological identity, political identity, and cultural identity as synonymous. It's a form of racial essentialism that would be obscenely bigoted if human populations were portrayed that way. In real life, cultures intermix. People immigrate. People convert and assimilate. Portraying a given culture as all one species, or a given species as all one culture, is stupid and shallow. So any attempt to portray a political power in Trek as multispecies rather than monospecies is a step in the right direction.
Besides, the Romulans probably descended from a single movement that left Vulcan 2000 years before and migrated to Romulus. It stands to reason that they would have been culturally and perhaps racially monolithic. If they were intolerant of telepaths or some other ethnic subgroup, why bring them on the migration in the first place? But if that monolithic group arrived at what they hoped would be a new homeworld just for them, and they found that one of the twin planets already had its own indigenous species, then it makes perfect sense that they'd subjugate them.