High construction costs with rising building interest rates

And compared to today, they have such much worse living quality. What you are saying is complete nonsense.

So now once again very concrete. Why is the housing situation worse today than it was back then?

To put it very simply: In my personal environment, the vast majority spent their childhood and youth in a new building from the 90s. These people are now being told that this 90s building is the be-all and end-all, but rather as a terraced house variant, since that is still affordable. If that is not available, then a 50s, at best a 70s shack will do, and to avoid freezing, a sweater. That is exactly what is called a regression in the housing situation. And even that can only be achieved with family support.

Of course, this is now a singled-out individual case, but it is exactly how it happens all too often. One must not forget the internal German migration movement to the cities. Jobs are moving from the countryside to the cities, and people follow. In the countryside, you had the spacious house, in the city the tiny rental apartment. That is understandable up to a certain point, but you still can't get it out of your head. And you also don't necessarily want children in this small rental apartment.

We are only talking here about the first generation that will have worse living conditions than their parents' generation

To put it very simply: In my personal environment, the vast majority spent their childhood and youth in a new building from the 90s. These people are now being told that this 90s building is the ultimate, but rather as a terraced house variant, since that is still affordable. If that is not available, then a 50s house, at best still a 70s hut, will do, and to avoid freezing, a sweater. This is exactly what is called a regression in living conditions. And even that can only be met through family support.

The parent generation is more the Boomer generation

that experienced the building boom until the mid-90s

I can no longer follow your jumps in thought.

Which generation today has worse living conditions than back then? Do you really think that everyone is looking longingly at the "old huts" that are not even renovated or refurbished? That is simply nonsense. People living in an unrenovated or unrestored 80s/90s house are at least living there. Whoever buys the house adapts it to the current conditions. New materials have been installed in the meantime (or are being installed now). Modern bathrooms, floors, windows, etc.
And already you yourself are living better in a 90s property than "back then."

But you are really missing the point. The Boomers significantly improved from their childhood in post-war houses to adulthood in a 90s newly built home, whereas their children have difficulty maintaining their childhood standard in a 90s building into adulthood and passing that standard on to their own children.

Oh yes, many houses from the 80s and 90s are still completely unrenovated. And where renovations have been done, they are generally more cosmetic improvements. Truly "modern" bathrooms are not free in renovations, by the way, it quickly costs tens of thousands because for modern bathrooms you usually have to change the arrangement of the connections alone, otherwise walk-in showers, etc., cannot be realized. That means all the pipes must be removed, the electrical system has to be redone, and many other things. You can do the demolition yourself, but I would rather leave the piping to the plumber and then he will not install cheap DIY store sinks and will demand a reasonable hourly wage. A "modern" bathroom does not just mean simply replacing a shower tray but a complete core renovation with everything included.

The boomers have significantly improved from their childhood in the post-war house to adulthood with a 90s new build,

Yep.

whereas their children have difficulties maintaining their childhood standard in a 90s building into adulthood and passing on the standard of their childhood to their own children.

They only know one standard from the mid-80s to mid-90s. When they buy such a house today, it is or will generally be significantly improved compared to the original year of construction, since it is renovated/refurbished. The standard remains at worst the same and is usually better. You don't really believe that such a house was completely worn down for 30-40 years and then this just continues seamlessly after purchase.

Oh yes, many houses from the 80s and 90s are still completely unrenovated.

But the original builders still live in them and not the next generation (who do something to it when buying).

By the way, really "modern" bathrooms are not free in renovations; tens of thousands easily go into them because for modern bathrooms you usually have to change the arrangement of the connections alone, otherwise walk-in showers etc. cannot be realized. That means all the pipes have to be removed, the electrics must also be new and many other things. You can do the demolition yourself, but I would rather leave the piping to the plumber and then he won’t install cheap DIY store washbasins, plus he will demand an appropriate hourly rate. A "modern" bathroom does not just mean exchanging a shower tray, but a complete refurbishment with everything included.

Nonsense again. If you renovate cost-consciously, you renovate with the property and not against it. You don't have to tear out all pipes or re-route electrics (for what reason in the bathroom?). You just modernize the shower, new floors/walls, exchange a floor-standing toilet for a wall-hung one, and "modern" sanitary fixtures turn an old bathroom into something completely new. Without a full refurbishment. So what, why must it necessarily be a walk-in shower? That's directly the demand of today. A low-profile shower tray is fine, modern, and a bathroom adapted like this for a relatively small budget does not significantly increase the standard? Does it really have to be a full refurbishment? If you think like you do, it’s no wonder that people believe a modern property is no longer affordable today.

Houses from the late 80s/early 90s are simply no longer affordable for the broad public in some regions (e.g. Rhein-Main), as they easily cost 500k+X. If the square meter of building land is sold for 500€, you won’t get the existing house with 550sqm of land for 350,000€.

And with houses from this era, often nothing has been invested yet (maybe the heating system once). You have a 35-year-old bathroom and even if you just retile it, etc., you quickly end up with 20k expense. In my circle of acquaintances (mid-30s), no one is doing a complete renovation because it’s not affordable.

In the "modern" bathroom, the toilet bowl has an electric connection. Didn't you know that? You can do a lot visually with light these days, the mirror has become digital, and much more. Bathrooms that are 30-40 years old do not allow all that. Do you need all that? Of course not. Is it part of a "modern" bathroom? Yes, absolutely.

If a 30-year-old bathroom has been well maintained, I would simply leave it as is and save the money, and tackle it later on a larger scale. But if you have to deal with it anyway because something major doesn't fit, then you should do it properly right away. And then one thing leads to another. In the end, however, it is still cheaper and less stressful overall than having to redo something else after 5 years. Better to tear it up only once every 40 years. Then you get a walk-in shower, underfloor heating, modern electrical work, updated water pipes, etc. all at once. Visually, you can also set new accents and follow trends (if desired) and avoid floor-to-ceiling tiling, etc. Just for demolition and plastering, you can still provide a lot of your own labor and yet receive staggering bills.

The previous poster also mentioned an essential point that often makes existing houses expensive: the plots of land are significantly larger (even more so with those from the 60s and 70s, which is why buyers there are very often developers who then build multi-family houses on them) compared to today. That’s why the space-efficient new semi-detached house with a tiny garden is hardly more expensive here than the tear-down house with a large plot that you basically don’t need anyway. The €500 is still reasonable, but it can easily be double that. In some commuter belt areas, especially those connected to the S-Bahn, it’s hardly cheaper than in the city. These are probably also the areas hardest hit for the middle class. In the city, owning a house was never normal, and in the true countryside, at least the land is still cheap.