My response was this:
Your question seems to be referring to the perception of a decline in civility in politics, or political language. It may be true in some ways, but here is my perspective: First, in the 20th century, polite and civil leaders in public forums committed some of the worst atrocities, like genocide, in interstate wars and civil wars. Does it matter if words are demure, when civilians and particular identity groups are targeted for violence and victimization? Second, there are plenty of counter-examples of lack of politeness, such as Khrushchev banging his shoe on the table in 1960? Third, the number of democracies in the international system has steadily been increasing since the Second (Cold War) and Third (1980s) Waves of democratization, which corresponds to overall less formality in political language.
What may be the most dangerous is not the decline in civil or polite language, but the weakening of democratic institutions or preferences for liberal democratic values in mature democracies. When institutions like an independent judiciary are threatened, or when citizens show preferences for authoritarian leadership and are complacent to (or acceptant of) weakening respect for human rights (at home or abroad) – these things are problematic. There are many examples of populist candidates and political parties in the Philippines, Hungary, Denmark, France, and Germany.
The map below shows which countries use the most angry language. By far, Iran uses the most angry language, followed by the United States, Venezuela, and France. This roughly corresponds to the use of formal language, which also allows us to infer about politeness. People are more formal and more polite when they are unfamiliar with each other, or when they are speaking to their superiors. It is possible that the decline in civility or politeness also is a reflection that many countries are broadly using less formal language with each other.