Exactly right. The idea that Romulans=villains or Romulans=sympathetic good guys is incredibly simplistic in terms of narrative drive. The whole idea of creating complex society, where the viewer needs to determine how they feel, is a powerful in fiction.Romulans are not a Hive Mind like the Borg, there are good Romulans and bad Romulans, just like there are good and bad Americans, good and bad Muslims, etc. Generalization is applying the actions of some individuals to an entire group. If the Zhat Vash caused the Mars attack than they would be responsible for the deaths of millions of Romulans as well, which is similar to how most ISIS' victims are other Muslims.
I love that there is the potential for Romulans to be both sympathetic and still have antagonistic tendencies and factions.