Pomo summer: Postmodernism is still shaping contemporary architecture, says Owen Hatherley, but its impact on social housing is an unforgivable legacy.

Everything gets revived eventually. And when it gets revived, it gets applause from people who originally hated it. The list is long of architects and critics who now praise the "icons" of the 1960s and lament the 'icons' of the 2000s, but would have been doing much the opposite 10 or 20 years ago.

One thing that Postmodernists were and are most certainly right about is the fact that the culture of architecture is strangely unwilling to admit that what it does is massively determined by fashion. Postmodernists themselves have been hugely unfashionable during the 2000s, but a slow revival is obviously taking place, seen particularly on this site of late.

It is, by the 20-year rule of revivals that seems to have pertained since the 1970s, obvious that Postmodernism's time has come. It's equally obvious that Postmodernist ideas either explicit (FAT and AOC being unabashed Venturi fans) or implicit (with such disparate firms as Caruso St John and Foreign Office Architects owing it a debt) are still shaping contemporary architecture.

However, for some of us, Postmodernism will not be forgiven lightly for what it did to architectural culture from the 1970s onwards. So here's the case against forgiveness.

First, there's several grounds on which it's silly, anachronistic or hypocritical to make Postmodernism into a pejorative. Decoration has been a part of 20th-century architecture even at its most apparently refined – as Postmodernists liked to point out, the I-Beams on Mies' towers had no structural role whatsoever. Already by the 1950s, such an apparent hardliner as Walter Gropius was off doing neo-Islamic domes in Baghdad and mid-century Ionic in Athens. The notion of a truly unmediated conjunction of form and function, if it ever existed, was probably limited by that point to some of the more banal, industrialised mass-housing estates.

For the same reason, you can't indict Postmodernism for its historicism, when various Modernists, from Basil Spence to Giancarlo de Carlo, were quite happy to design in something approximating to the local "vernacular".

Finally, commercialism, one of the usual things that Pomo is blamed for, had never really gone away, bar maybe for a few austere years in the second half of the 1940s. It was part of Modern architecture from very early on, in the so-called Reklamarchitektur ("advertising architecture") of Erich Mendelsohn's department stores and cinemas in 1920s Germany, which were major sources for the International Modernism of the 1930s and after. Rather, the problems with Pomo boil down to two linked constructions – historiographical and political.

The thing that distinguishes Postmodernism from Mendelsohnian Reklamarchitektur, 1950s "local Modernism", 1960s Pop Architecture or the clearly totally anti-functionalist forms of Googie or Expressionism is a partly aesthetic, partly political favouring of leaving things as they are.

If you read, say, Erich Mendelsohn on Times Square, he loves and talks up the dazzling spectacle of the neon advertisements (hated then, by most right-thinking intellectuals, as Vegas was in the 1970s), but he doesn't accept them. They might look fabulous at night, he points out, but they look awful in the daytime, when you can actually read them – depressing mixtures of adverts that treat you like an idiot and political slogans that aim to enforce that idiocy. He imagines that he'll do something different with neon, smooth it out and design buildings that incorporate it on their own terms. Which he did. When Venturi/Scott Brown looked at neon signs and billboards 50 years later, they were well aware of this precedent, and their way of differentiating themselves was to deliberately disavow critique. This is how it is, and it's "almost all right".

This may have its virtues as sociology, perhaps, but it was dangerous nonetheless. By refusing to criticise the object world of ads, consumption and spectacle – in somewhere as exploitative as Las Vegas for God's sake! – they created an influential equation. Consumer choice is always authentic and good, and to argue otherwise is to be a snobbish aesthete.

Defenders of Pomo who combine their liking for it with left-of-centre politics can point to the way that early Pomo was linked to local campaigns and ideas of "community architecture", against the collusion of big business and the state in places like Greenwich Village and Covent Garden. The architectural results of those events are pretty minor, but in the West Berlin IBA of 1987, Postmodernist ideas about streets, complexity, juxtaposition, decoration and context did result in some of the most interesting social housing schemes in a city already full of them.

But there is a reason why Postmodernism and the Thatcher-Reagan revolution became so closely linked. Charles Jencks's inaugural manifesto-compendium on Postmodernism included within it a staged knife attack in Robin Hood Gardens, one of the social housing schemes written off therein as a social failure largely because of its design. A great way of intensifying the rationale behind a design choice was the old Ruskinian appeal to morality. Modernism meant bad concrete estates full of bad walkways and bad open spaces and a bad lack of ornament and tradition, which produced bad people committing bad crimes. If you think that's a reductio ad absurdum, read practically any book on architecture and planning published between 1975 and 1995. The results, for those in those apparently "bad" buildings, would be drastic. The new "common sense" was that their housing was so awful that it probably needed to be demolished – eventually, as you can see in, say, London's Cressingham Gardens, no matter how much residents insisted they liked their Modernist houses.

It's not Postmodernist architects' fault that in most of the west, social housing stopped getting built at around the time their ideas came into fashion. However, the fate of Modernist social housing is partly their fault, in that they willingly gave the aesthetic alibi for a political campaign.

You can try to imagine, if you like, a counterfactual where Pomo didn't mean dockside condos and bumptious HQs for big business but became a better kind of social architecture than Modernism could ever produce. Maybe the IBA came close to that. History, however, deals with what did happen. Overwhelmingly, Pomo ushered in a new wave of architectural determinism – worse than that of Modernism, to a large degree, in that an optimism about human beings, their intelligence and their civilised nature was replaced by an aesthetic which assumed that the most crucial point of intersection between aesthetics and users was the cash nexus. And if the plastic broken pediments and fibreglass Doric columns are gone, that spirit certainly outlives it.

Owen Hatherley is a critic and author, focusing on architecture, politics and culture. His books include Militant Modernism (2009), A Guide to the New Ruins of Great Britain (2010), and A New Kind of Bleak: Journeys Through urban Britain (2012).