>Are they?
Yes, they can be.. providing you are comparing apples with apples. According to [0].
But that is not really satisfying without numbers is it?
So lets take the first example linked in your reddit post. The Potsdamer Palace. It is the most interesting example as they went to some effort [1] to reconstruct the facade as closely to the original design as possible, including the brickwork skin and hand finished stonework. Of course internally it is all concrete and steel, but you would never know that from looking at it.
Built for €120m [2], 35,000sqm GFA, 19,000sqm utilities (a wopping 35%) and only 390 offices. About €2500/sqm for the construction price, but at about €200,000 per office. A standard low rise office in germany seems to be close to the €1500/sqm range. But you would expect more like 20-25% utilities floor area and lets say 1 person/10sqm (ie. open plan office seat) for occupation. So for the same size office built with standard construction techniques, this floor area would be about €70m including utilities, but only €15,000 per office. (if you calculate out the €200k /office of the example with the 3500 offices of the standard office, that is a €1,076m price, ie. at least an order of magnitude).
Ok, so we are not talking about a typical office building here. It is also very significant that the examples chosen were all institutional, rather than commercial ie.the symbol was more important than the return. The point is that the original construction techniques required significant additional human labour, additional area for structure, but also light, servicing, and ventilation, and additional costly materials. All with a reduced usable internal floor area.
But sure, just stick something on the façade and call it a day right? But, if you already have a working façade system which gives you more saleable floor area, as a developer, you would sack the architect that proposes something else. So yeah, we have some power over the façade, but not that much.
So I guess the resistance to 'traditional' is mostly in the ''s. But also in that contemporary architects often care about process and user experience over formal traditions.
The other funny thing about this argument, is that the very same objections were held towards modern architecture in the time of the original construction of the Potsdamer. It was broadly in the style of the late Roccoco (in particular, a Prussian variant), which the Neo-classicists thought was ugly and modern. The Neo-classicists looked back, copying the original renaissance classicists of course, who were copying the styles of the ancient Romans, who had migrated a good deal from the ancient Egyptians via the Greeks. Taste is an old argument.
[0] me, working in the industry for 20yrs.
[1] https://www.landtag.brandenburg.de/en/parliament_building/84...
[2] https://www.landtag.brandenburg.de/media_fast/5701/Schriften...