I do not see why this is interesting or surprising.
Rome needed a state religion to bind their civilization together.
They did not have one. They had a household religion, every house had their gods and the patriarch and matriarch were their priests. This did not lend it's self to elaborate public ceremonies and a priestly class that could be controlled by the state.
Greece had a fully developed state religion and it was just sitting there so the Romans grabbed it and ran off with it. The other major religion in the area at the time would have been the Phoenician. Let us be glad they did not pick that one.
After giving it a dye job and hair cut they now had their state religion. Which they took everywhere.
It would be like being surprised to find bath houses.
Also, remember that there were Greek colonies in Sicily, Corsica, Sardinia, and perhaps in mainland Italy as well. So there were surely Italians already worshiping those Greek gods before the Romans conquered the whole area. So they didn’t have to import the religion all the way from Greece, there would have been local priests and sybils practicing it in their own lands.
Apollo also didn’t have roots in ancient Greece, the Etruscans were from the east, and their Apulu (sp?) was picked up by the Greeks, then the Romans.