I mean, really, it's ROME right? In what is ITALY. So, shouldn't they at least be speaking like Stallone or someone from the Sopranos??
Answer on In the movie Gladiator, why do they speak in, what seems to be, an English accent?
Maybe because Russell Crowe is Australian and Richard Harris is English. There's no point in trying to put on a Roman accent - no one knows what it sounds like. A bad accent distracts from the film more than it helps.