As both your link and the broader scope of European history indicate, Roman society of 100 CE was in fact in the midst of a many-generations-long decline into irrelevance, so this is perhaps an unintentionally apt citation.

Well that depends. Comparing Europe now and 100, 250, 500, 1000, 1500, 2000 years ago makes now appear much better on various metrics: political & military stability, human rights, women's rights, life expantency, death from disease and plague, famine, social equality, the wealth of the lower 50% of the population, gay rights, racism, manual labour, religious toleration, etc. etc.

As tlogan's response notes, the distinction to draw in judging 100CE-era commentary is not between Europe in 100CE and now, but rather between Europe in 100CE and the ensuing decades and centuries, which demonstrated that the naysayers of 100CE Europe were completely justified.

That things then swung back upward again is cold comfort to the ancient Romans and does not demonstrate that things could not swing downward for our civilization.

The history goes in waves... The great Roman culture was in generational long decline and eventually replaced by "Dark ages". "Idiocracy" is basically something like "Dark ages".