The medical/tech advances alone would make my point, but you seem to want to ignore those, so I'll stick with social aspects.
Our populace is more educated, less violent, healthier, and wealthier than we were in the 1920s. Heck, on Wall Street the 1920s was a decade of greed and moral decrepitude (if you get into that sort of name calling) that is possibly only rivalled by the 1980s. Go back 30 years, and you are squarely in the 'Gilded Age', where the Senate was completely controlled by large companies (to the point where the companies simply picked candidates and ushered them through state legislatures, because Senators weren't popularly elected yet). After that came the Progressive years, where we learned that our meat was lethal and other things, and women finally got treated like human beings. How could any of those decades be considered better than the current one? Sure, women's suffrage was a great accomplishment, but only because the reality to that point was so bad.
My brother has a saying... "progress, not perfection". American history has been exactly that. Sure, there are temporary setbacks (no one can argue the 1930s were better than the 1920s really), and there are local setbacks (1980s Detroit?) but the overall story is progress. Thankfully the small victories accumulate faster than the setbacks, leaving us with a better society all the time.
I guess if we need the jeremiad to motivate us to make progress, then that is fine. I was simply commenting that it's disingenuous to pretend that it's somehow different this time. If it really were different, you wouldn't be sitting around musing about it, you'd be dealing with a collapsing society.
But I guess if you realize that, the jeremiad loses it's power, so maybe it's better we keep pretending that things are going to hell.