Shooting from the hip, I would say it is in the very nature of progressives to reject the status quo, no matter how good the status quo might be.
I mean, we just got out of an election cycle where the sitting President brought us a couple years of outstanding economic prosperity, avoided tangling us in new wars, helped America appear strong in the face of its adversaries, and even earned four Nobel Peace Prize nominations for his work in stabilizing the Middle East...yet people were up in arms about what an evil man he was and needed to not only be voted out of office but to be completely eradicated from our social consciousness. And for what, really? Perceived character flaws? An abrasive personality? Allusions to being a Russian sleeper agent that - in spite of the best efforts of Congress - turned up zero evidence to being true?
Yet more than half the voting population could. not. WAIT. to get rid of him. They cheered. They cried tears of joy. They spoke of a great darkness having been ended. While, ironically, most of the people making these claims benefited GREATLY from his time in office. Go figure.
I think we live in a society that is so obsessed with correcting every perceived "wrong" that we no longer have the ability to appreciate how good things are, when they are good.
So you ask about tradition and what we are so afraid of. And the only answer I can give you is that things are so good in our lives that we're looking for non-existent battles to fight. No reasonable person would assume that saying "Merry Christmas!" is an intended insult against atheists and non-Christians, but in the name of the god of political correctness, we must thoroughly denounce and chastise those who wish us that because, "not everyone celebrates Christmas, you bigot!"
What traditions can possibly be safe?
Thanksgiving? Oh, you mean white-people-colonization-celebration-day?
The 4th of July? Oh, you mean celebration-of-white-supremacy-and-slavery-day?
Memorial Day? Oh, you mean remembrance-of-American-wars-of-aggression-day?
It doesn't matter what tradition you choose; someone will find SOMETHING to denounce it over. Because that's what we do now. We might as well declare it the new national pastime.
This is why we can't have nice things.
Does the tradition produce a good party?
The super bowl yields great parties, so let's keep this tradition.
If a tradition doesn't make for a good party, drop it, or change it so that it does.
War isn't a party. The American Civil War wasn't a party. But students at Vanderbilt made it into a party with a set of party games themed on North vs. South. Nobody died of a musket ball during the party. People got drunk and were merry. Then leftists at Vanderbilt attacked the partiers as white supremacists.
Leftists events aren't fun. They can't party. Trump rallies are fun. TPUSA events are fun. Republicans know how to party. Republicans should launch a charm offensive. I'd rather party with Republicans than Democrats.
A leftist riot isn't a party, especially if your store is looted. The Capitol Tea Party was a party. They partied and posed for pictures. It was a meme mother load.
Republican memes are funny and Democrat memes aren't.
It depends what the tradition is, and why it is retired. Do you cling to tradition because it is tried and true, or just for arbitrary reasons and because it is what you know? I was with you for the most of it, until you made it about religion. Your Oktoberfest / lederhosen example is apt - something fun about honoring the history and culture. I am not religious in the slightest bit, but I still enjoy honoring some history and culture of being Jewish. But again, not everything is good just because it is traditional. Slavery was tradition. Executing blasphemers was tradition. Treating women as property was tradition.