Le Corbusier as I Knew Him (1977)

>The goal of Haussman was [...] to modernize and get rid of the obviously impractical designs.

That, and make the city easier to pacify with military force. Also it wasn't so obviously impractical. There was a lot written at the time about how Haussmann was destroying Paris by tearing out her heart and splitting her up and so on and so forth.

Corbusier's central thesis was that the world had progressed but architecture had not, to the point where previous architecture was obsolete. With the nostalgic and excessive neoclassical style of the beaux-arts dominating the 19th C. it wouldn't've been hard to get that impression. From the tellingly titled "Towards a New Architecture": "Engineers have been busy with barrages, with bridges, with Atlantic liners, with mines, with railways. Architects have been asleep." He was not alone in that conception. He wasn't even the first of the modernists to articulate it. This desire to make a clean break with existing tradition (which you cast as the unique and defining sin of Corbusier) is more or less the foundation and the entire point of Modernism.

Here's two examples that spring to mind. Loos writing in 1910ish alleged with new industrial processes the waste encouraged by the fact that styles go out of style made ornament criminally wasteful, so he advocated for architecture free of ornament. Theo van Doesberg and the rest of De Stijl gang took it in another direction around 1917, attempting to distil everything into category or continuum. In art and architecture this meant right angles and straight lines only (because angles are binary duh, though sometimes 45-degrees was okay), only black, white and the primary colours allowed, and the inside and outside of the building, painting, etc. existed as a continuum (Mondrian was a member for a while)

(It was also a political marriage of convenience because in the '90s, railing against welfare was in vogue, and HOPE VI generally did not result in 1:1 replacement of public units, so it was a backdoor way to reduce the population on welfare.)

I don't really think the issue is density. Plenty of low traffic, low density suburban areas have high crime as poor people move into the suburbs; public housing had few eyes on the street because the design intentionally kept out passersby, and if anything suburban neighborhoods with high walking distances, mazelike streets and inconvenient, unpleasant walking environments are more extreme than that, and also have lower amounts of residents to boot. At least in NYC (and probably true of a lot of very inner-city housing projects) the towers in the park usually replaced existing urban neighborhoods at far lower densities than what had previously existed, because so much of the land was just idle greenery (that usually wasn't useful, in the form of small, segmented lawns often fenced off). Compare that with, say, Vienna, where the masses are housed in public housing in large midrise (5-10 story) buildings.

Coincidentally, this large midrise form factor is also what dense gentrifier buildings look like in many cities around the US, from Seattle to DC.