Hm, I will try to reply to this as open mindedly as I can. I think this is a very difficult subject to discuss, because it can escalate into mindless fights very quickly and as you may have taken from my previous post I have a quite strong opinion on it. Nevertheless I try to keep an open mind. For example I don't want to judge someone for being a Leipzig fan, I think people can have very different reasons for being a fan of something and I don't want to ridicule them for it. I might not entirely comprehend their reasoning but that shouldn't take anything away from them. I don't mind the fans, I hate the "product".
When you started your post with the "unpopular opinion" bit I expected not to agree but I was curious about the arguments to come. Honestly that left me quite disappointed because there is basically one argument (Leipzig invest their money well, clubs like Hamburg are idiots) dragged out a bit. I am actually not even disputing either of them. Leipzig are indeed doing a pretty good job most of the time, Hamburg have been mismanaging to a comical extent and other clubs like Schalke, Stuttgart or Köln have made significant mistakes in the past. What I am disputing is that they had comparable prerequisites.
Leipzig are a club and team created with a vision - a style of football employing a lot of young players as promoting a brand - starting in the fifth division. Enormous amounts of money were invested into team and infrastructure, nevertheless it took them three years to get promoted from the fourth division. This lull in development was only possible for them because they had constant cashflow which was independent (!) of sporting success. This is what has distinguished them from any other project with less monetary backing - they could and can afford to make mistakes. This ability probably makes them look a lot better than they are. You can afford to make these mistakes if you can just buy yourself out to look brilliant the next day. This ability to make mistakes is to this day what gives them an edge and what leads clubs with less security to make questionable decisions. You disdainfully point out that clubs like Hamburg plan for the short term, which has multiple reasons. Some of these are issues that plague "traditional" clubs: Inflated expectations from their huge fanbase, a vicious media coverage in Hamburg and an unhealthy dependence on Mr. Kühne and his money. All of this should not be swept under the rug and a lot of this is self inflicted but it all comes down to them not being able to afford their transfers to fail miserably. They had to work with limited budgets fighting relegation.
And sure, you can point out positive examples like Freiburg or even Dortmund making their own luck without the backing of someone like Red Bull, but this is oftentimes tied to somewhat lucky personnel decisions and once that personnel is gone it may go back downhill again (Klopp, Streich). And I have now only reacted to your argument and not talked about additional aspects of a club like Leipzig that annoy me like their competition distorting connections to Salzburg/Liefering/New York, their obvious bending of DFB/DFL/UEFA rules (with these bodies not really doing a lot to fight it), their blatant bending of the rules of being a "Verein" in Germany obviously not wanting any members that could want a say in club matters (not sure what fees are nowadays, they sued to be around 700€ as far as I know) and I could probably find more if I took the time.
So yeah, feck plastic clubs. I understand if people don't care that it is unfair (football business is unfair, I get it), the worst thing for me about this development is for the fans. Plastic clubs like Leipzig take up slots of clubs that actually have deeply ingrained fan bases. Of course that doesn't give you any kind of right of inheritance but it still hurts me that fans of clubs like Duisburg, Bochum, Kaiserslautern, Nürnberg, Braunschweig, Aachen, 1860 München, Karlsruhe and yes, Hamburg and Stuttgart have to see their clubs go to shit while we have clubs like Hoffenheim, Leipzig or Hoffenheim in the Bundesliga who can't even fill their stadium in European games sometimes. And finally, I wanted to make some snarky reply to your last paragraph turning it into the opposite but I noticed myself sounding like a dick as well, so I didn't.
I used to think similarly, honestly. Strongly disliked Wolfsburg, Hoffenheim and Leipzig, tried to convince people - including myself - that Leverkusen actually has a history and belongs into a different category. However, I actually am a person that gives a feck on tradition in all other aspects of life. I'm very interested in startups, tech, development and all that stuff. I dislike people and entities that refuse to change or improve themselves. And all those tradition clubs that faded into nothingness are actually the embodiment of "we've always done it that way and it was successful so we keep on doing it like that". So I came to the conclusion that all this blustering about tradition is bullshit to me and I actually prefer the disrupters who innovate and make things better.
People are used to clubs promoting former players into very important jobs, quite often even into the most important positions there are (managers, directors, presidents, etc.). That's such a common practice that few really question it but if you really let that sink in, you understand how the silly this common practice actually is. Professional football clubs - even the small teams - are companies that earn millions. Their employees earn millions. And they regularly appoint people that don't even have the slightest qualification for such jobs. People who quite commonly received no education after their a levels, in many cases even earlier. Usually you need a university degree plus years or even decades of working experience to be even considered fit for such position. No wonder they fail.
See, in the end, all football clubs are businesses. When people describe Leipzig as a "plastic club" or "artificial", I don't understand where they see the difference to their very own team? It's not like Red Bull has altruistic, sentimental or entertainment-oriented motives or something along those lines, they invest the money because they expect an advertising impact in return, just like the sponsors of every other team. So essentially, their business model is the same as those of every other club in the league, they simply take it one step further than anyone else. It doesn't matter where they started, it was an investment in the future that wasn't expected to pay off right away. This kind of long term oriented thinking is what most other clubs - and especially those that fell from glory into insignificance - are lacking.
What I feel and what really grinds my gears is that all those ranting about plastic clubs are - if you really think about - just angry that someone came, did it differently by thinking outside the box and - suprise, suprise - was successful with it. They abandoned common practices many people deemed mandatory. They broke the conventions and people are mad because of it. They didn't prioritize short term over long term, they did the exact opposite. And contrary to what people were expecting and what they would've done with the RB money (spend it on the best players, the early Chelsea/City/PSG strategy) they behaved totally differently and invest it in an exceptional scouting network, young talents, their academies and infrastructure. There are so many young players who are where they are thanks to Leipzig. And it's the same with coaches. This is what I call an enrichment for the Bundesliga. Not a club that is managed poorly but creates a warm feeling of nostalgia when you see it's shirts because it reminds you of your youth. If you observe Leipzig, you get the feeling they have a strategy that they pursue. A team with a mission. Very few clubs in the Bundesliga can say that about themselves, IMO.
So from my point of view, the only argument you brought up and I can relate to is the one about the full stadiums. Yes, that's a real quality of the Bundesliga. But if that was the decisive criterion, we could as well just vote democratically who should play in the Bundesliga. After all, we are talking about a sport and sports are about competing against each other. And as much as everybody may love it, those competition isn't won on the pitch but mostly in the offices of the people who make strategic decisions for their clubs. And in that regard, Leipzig currently trumps every other club in Germany, like it or not.
That may have been calculated oftentimes and has been held to his credit but he has lost his mark recently and I am really not sure when it changed or if he has just always been an insufferable cnut. I can't help but feel a good deal of satisfaction from seeing him tarnish his legacy in the way he does.