Nothing suggests to us that the morality of Roman times is capable of existing now. You say “societal values may have changed” but that’s the entire thing. They’ve changed. We have shifted the society to where this kind of public torture would never happen. It can happen again and people are capable, but not unless society shifts.
And the trends show that while people are divisive, their morals are very closely related. You may not agree on abortion but most people agree we shouldn’t kill prisoners inhumanely.
People completely misunderstand morality. People are not currently capable of tolerating this kind of thing. If you think so, do a survey and I’ll eat my hat.