Italy has been partially put in the games thanks to Civ 4 HRE, where Italian cities were used, and Civ 5 Venice. I think the primary reason they haven't got in is the whole "Rome is the capital situation" which could have been avoided this iteration, however.Then the people from Firaxis A) either never passed primary school, or B) have another criteria to pick civs after 6 games and over 50 civs.
Still the vast majority of people associate Fascism with Germany, and that doesn't stop their inclusion, nor Fascism appearing as a government option.Agree all nations did some terrible stuff in their history, that is not a reason to leave out any option.
Still, if the great achievements of italians ancestors are reasons to add them it should be also valid to point the negative actions.
I think them being the birthplace of fascism is at the bottom of reasons to not to include them, if that's even an issue at all.