I think the Romulans and Cardassians have many things in common. Both strike me as being totalitarian and Fascistic. Especially the Romulans and their devotion to the Praetor. I think by focusing on devotion to the leader and the state they have found a way to channel their more aggressive tendencies away from "savagery". I know we like to think of the Romulans as xenophobes, but perhaps they just like to prioritize things. The Federation has been a secondary priority from time to time. The Feds are probably lucky the Romulans are a "buffer" between them and the Rommies first priority.