Well, a lot of Romans had quite different noses. I don't think that's the most common one at all.
Marcus Porcius Cato:
Scipio Africanus the elder:
Cicero:

Caesar:
Marius:
Sulla:
Pompei
Marc Antony
These were the most prominent men of their day. As far as their noses are concerned I'd say the most common trait was a high bridge and the sort of "bump" right below it, with Pompei being the exception.
I think you're confusing A "Grecian" nose and a "Roman" nose.
They didn't have that straight "Grecian" nose, which may have been just an idealized version of a nose even in Greece, used for every statue, but not necessarily on most people.
Romans, especially of that period, produced very realistic busts of their leaders, imo.
The most common "feature" imo was that distinctive very broad skull coupled with a tapering almost triangular face, and the small mouth.
Richard Armitage has a Roman nose in my opinion; Italian as well. :) If his eyes were different I'd definitely guess Italian.
Jovialis too has a Roman nose, although not as long. My son and father had it too, minus the slight dip right at the eyes.