Aren't they supposed to be even more emotional than humans by nature, with the logic thing being a result of having a cultural emphasis on repressed emotions and rational thinking? It doesn't seem too absurd for people in those circumstances to use any outlet for emotional expression they can that doesn't come with loss of social status.
Yes, that's exactly right. Their aggressive base natures resulted in both a nuclear holocaust on Vulcan and Romulans going into (probably self-) exile. At some point in there, Surak came along and brought Vulcan into a golden age with the embrace of logic and the purging of emotion.
Honestly, with how racist Vulcans are constantly, and all the corruption in the High Command we see in Enterprise, I think it's much more likely the Romulans were forced off of "Vulcan"