I don't have direct experience in construction, but in a past life I worked in two academic IT departments; it always pays to be good friends with the facilities people in that world. Plus, my more direct co-workers were the ones who needed to run conduit from point A to B. So I have some direct second-hand experience and plenty of bar-stories. American Universities almost always have one or two Brutalist piles lying around, and my experience was no exception.
I was really surprised to learn how much maintenance concrete needs; it cost at least half as much as wood averaged over the life of the building. Acid rain is nasty, rebar rusts and causes spalling, penetrations such as conduit quickly leak. When I said painting concrete, I really meant treating and coating to preserve the material. So, now you have to pay almost as much to maintain this structure - then you get a request to install a new exterior security camera, or run some cat5 to the ceiling for an AP, or add a door between labs, and what would be a one-day job in a wood- or steel-framed building is a week-long torture session of drilling.
Of course concrete isn't evil - it clearly makes the modern world possible! And there are some successful Brutalist buildings. But the Brutalist fetishization of it certainly has not stood the test of time.
Another specific Brutalist feature - particularly espoused by Louis Kahn (not exactly a Brutalist but close enough) - was that the building services, e.g. HVAC ducts and the like, should just be exposed. In his mind, it was awkward and sort of dishonest to try and hide them, so don't bother. As a nerd, I appreciate this sort of transparency, but the poor conduit jockeys were tortured by this. The consequences are subtle: instead of risers and service ducts, each individual conduit is visible and has its own penetration when crossing a wall. Which means: more drilling when you need a new EMT run.
Anyways, this is just a series of war stories. People like to joke that software "engineers" are not real engineers, and this is absolutely true. However, I think experienced software developers have a good sense of just how hard it can be to predict future use and tend to design with that in mind. It has been my personal experience that even experienced architects have not gotten the same feedback cycle, so the facilities department has to bust out the Boschhammer again and again.