"Punic Wars" cover centuries of Roman history so it's, again, very weasely to say that Rome wasn't expansionist before then. Especially when the first war was fought specifically so that Rome could take Sicily, which was not part of the peninsula and was inhabited by a different lingo-ethnic group than the Romans. Or how the Second Punic war ended with Rome occupying Spain, or the Third with North Africa. And all the meanwhile Rome was busy fighting in Greece and Asia Minor to occupy their territories as well.

You seem to think that the Roman conquest of Italy was somehow distinct from their other conquests when it really wasn't. Rome subjugated their Italian neighbors in the same way they subjugated neighbors outside of Italy, it wasn't like they expanded in a "settling way" in Italy but in a different way everywhere else. As per my previous comment, referring to Italy as Rome's "core territory" is an anachronism. There's a reason the peninsula was dissolute for over a millennium after the Western Roman Empire fell; there wasn't a single unifying culture in Italy. After the state collapsed all of the Italian regions split apart and had their own regional identities.