This was also a time of far heavier air pollution than we today ever experience, at least in "the west". The typical multi-family building were therefore built not right at the sidewalk, but about 15m further back. Adjacent buildings no longer connected, but had similar spacing. The fraction of open space vs that used by buildings easily tripled, and the free space was planted with grass or brushes.
This was also the time when mixed zoning was mostly abolished in favour of homogenous residential or commercial areas.
As it turned out, this style isn't necessarily what people want. It tends to be too quiet, distances increase linear with lowered density, cars became somewhat required, etc. But the motives were mostly pure.
Bear in mind I'm in the UK, where Europe's post-war rebuilding was also large part of the motive. The American experience was necessarily a little different - no bomb damage, and a large profit from WW2, thank-you-very-much.
The huge areas of bomb damage, and decades of soot and other pollutants meant many of those fine classic buildings were looking old, tired and in need of sand-blasting, or at least a good wash. The 50s brought coal restrictions and clean air legislation, so pollution and smog had passed. Cars weren't yet common. Looking to the future concrete was "clean", and very much of the Jetson's future, and you got so much more of it for every pound spent. Steam trains, and Victorian gothic fussiness were of the mucky past. Yet unlike marble, granite and even sandstone and brick it so often weathers and ages horribly.
There was, as you note far more space - and in architect or promotional artistry before they were built this usually had trees, planting, and very often a view through trees. The other style was of people and cars as cells in the futuristic city organism - that Jetson future once again. The 95% reality had a few feature trees set in concrete or flagstones, some feature planters for flowers - horse trough or hot tub sized that in the sea of concrete looked comical afterthought. By the 70s the trees most especially were dying, horribly sad or missing. Turns out mature trees need more than 2 sq m of water capture. I remember very little grass in the brutalist bits of the city I grew up in or those I visited in the 70s and 80s. The sweeping walkways in the sky meant walking a mile to cross a road, or endless steps - horrible if mother with pram, and lastly plenty of dark gloomy spots to get mugged or lost in.
The pre-war modernist, or the garden city movements, and even pre-war social housing had, in the UK, far more of the natural world, grass, large grass verges with mature trees and play spaces or parks. They hadn't yet discovered separating shopping centre from housing, so they were still working communities.
So yeah, it's easy to see why they tried and the motives that brought them, but it's as easy to see why it so often turned out dystopian nightmare to be demolished as soon as affordable. We'll be stuck with those car-first choices for a century though. Today's alternative of finding lowest possible bid unless it's a feature tower block isn't that much better.
But I wouldn't idolise pre-war architecture. There are some shockingly awful 1930s estates around London, and they're almost as dispiriting in their own way as archetypal brutalist tower blocks.
The garden cities are much more pleasant, but then you're not comparing like with like. Tower blocks were built to replace Victorian slums, with relatively high population density in both.
Some of the original designs were terrible, but sometimes they can be salvaged.
https://www.theguardian.com/artanddesign/2019/may/12/grand-p...
You're completely right about the brutalist campuses, btw.
Maybe egalitarianism isn’t as humane as it seems. Maybe if you bring everyone down to the same level, you find that you’ve reduced everything worth striving for to rubble.
And maybe all those artisans and decorators the modernists drove out of business deserved to make a living too.
Only it's really not that neat. When the brutalist monstrosities (you may correctly infer I don't like most of them one bit, though I do like much modernism) were being designed and built post-war, brutalism particularly was embraced as enthusiastically on all parts of the political spectrum. The mood was to build a "better world" and to borrow a cliche, embrace the "white heat of technology". Futurism, science, nuclear and modernism - including brutalism - was good. End of. Many fine examples of classic architecture were levelled, like the oft mourned Penn station, to put in an awesome, imposing brutalist slab that was looking tired and shabby within a decade. I'm sure the comparative cheapness and quickness of build won more fans in one part of the political map though.
As people started to live in them, use them, and live around them, it very rapidly became clear that brutalism - like much post-war architecture - didn't give a toss about humans. That was the real exciting new development in post-war architecture. The vision was inspiring, the reality was counter-productive in so many cases, as the scale or the amount of extra walking required wrecked the reality. They may have been impressive to look at, but so frequently fail to work as a building, or for people.
There are a few brutalist that work, and far more considered modernist, but in the main I call the brutalist experiment failed for those who have to use, inhabit or visit them. The ones that really work, seem to have one common feature - they remember the humans - you know, those things that use buildings? :)