Let me be upfront: I suspect that the below is not going to answer your question. Or at least the specifics of it. But I do want to provide some of the long-term historical context. So I have very little to say about the 1950s boom in Soviet housing stock but I can hopefully shed some light on what this was in reaction to.

Just as a note before we begin, I make numerous references below to Moscow. This is largely because it is probably the best studied of the major Russian metropolitan areas. Keep in mind however that both it and Leningrad enjoyed privileged access to investment and resources during both Tsarist and Soviet periods. As a rule, lesser cities/towns were worse off than the major capitals and conditions in new industrial cities of the 1930s (eg Magnitogorsk) were significantly worse again.

So, let me give you a quick tour of early Soviet housing policy and its permanent state of crisis.

The major Russian cities had traditionally suffered from a shortage accommodation, going back to the late Tsardom. This was largely a product of supply (new builds) not keeping up with demand (migrant workforce as part of late 19th C industrialisation). Overcrowding was rife and good accommodation too expensive for most young peasants migrating to the city. Some 9% of accommodation was communal - a relatively high amount at the time (Bradley). Oh how things change.

Residential construction largely came to a halt during WWI, due to a lack of men, materials and capital. The Civil War saw widespread devastation of housing stock, both through war and as a result of the shortage of heating fuel (which boded ill for wooden houses). Much of this was replaced with low-quality wooden residences but Peter Gatrell estimates that available living space probably decreased by approximately 15% between 1913 and 1923 (Davies et al). This helped give rise to one of the most striking features of post-revolution life: the communal apartment, in which several families cohabited in a partitioned flat. The resulting drama is almost omnipresent in immediate post-revolution works, such as Bulgakov's Heart of a Dog.

As the urban population began climbing upwards again in the 1920s (Moscow had surpassed its pre-war population by 1925) this problem became even more acute. But while the housing crisis got plenty of publicity in the 1920s, here was little action to resolve it. This was due to the same old reasons: shortage of men, materials and investment. In addition, the building season in Russia was/is relatively short, June - August, and that private construction which did take place was typically in wood and of low-quality. (Carr has a good discussion on this.)

(What is worth noting that that the NEP nonetheless saw an important shift in attitudes. Rent was abolished and, while private housing didn't disappear, the state assumed the duty of providing accommodation. It just didn't do this very well.)

This pressing issue became significantly more so following the onset of Stalinist industrialisation. The urban population soared - increasing by over 50% between 1926 and 1936 (Davies) - as peasants flocked, in their millions, to the cities and their factories. This was late Tsarist migration on steroids.

At the same time, the mad dash for industrialisation meant that the regime was unwilling to invest much on housing and related sanitation. This was well behind industry on the allocation of capital. To give an indication as to the priority that housing had in the 1930s, during the Second Five Year Plan (SFYP) of 1933-37 the construction of urban dwellings amounted to a mere 19.8% of the planned target (Zaleski). And this was in a period that, lying between the manic industrialisation of the first and manic rearmament of the third, was actually relatively kind to consumer needs and the 'third sector'.

So under-investment in housing stock was generally chronic during the 1930s, barely keeping up with the NEP levels of construction and entirely out of synch with the waves of migration into the cities. A survey of Moscow in 1936 showed that 6% of occupants/families lived in accommodation with more than one room, 40% lived in one room, 23.6% had part of a room, 5% lived in kitchens and 25% in dormitories (Nove). And this was Moscow, a privileged city. Where there was no existing infrastructure, ie in the new industrial cities being developed, a sea of tents, mud huts and wooden dormitories might spring up (Kotkin paints a vivid picture in his Magnetic Mountain).

This situation, understandably, only got worse after WWII. Not only did residential construction cease but there was significant deterioration in the stock as maintenance also came to a halt. Plus of course the small matter of the invading German armies. Filtzer estimates a total decline to the housing stock of approximately 25% during the war years (Furst et al).

There was finally increased investment in housing during the post-war Stalin period but this still lagged well behind the rate of urban growth. The picture from the 1930s largely persisted: cramped communal apartments and dormitories, many with little to no sanitation. But priorities lay elsewhere.

This didn't change until the post-Stalin era, as the repressive state gave way to a more materialistic bargain with the emerging 'middle class', the 'Big Deal' in Vera Dunham's phrase. I won't go into detail on this or the housing revolution (see my original disclaimer, above) but it's worth noting that construction of housing rocketed after 1953. By 1960 there was almost tree-times the living space being added to Moscow annually as there had been in 1955 (Colton). Nationally, available living space doubled between 1955 and 1959 (Nove).

And this is where cost comes in. Yes, the Khrushchyovka and later monoliths were dull and grey but they were cheap. And they had to be - it required an immense investment, over many years, to address a housing crisis that had persisted for decades. And sometimes, as Stalin is reputed to have said, quantity has a quality all of its own.

Sources

• Bradley, Muzhik and Muscovite

• Carr, Foundations of a Planned Economy (Vol 1)

• Colton, Moscow: Governing the Socialist Metropolis

• Davies, Crisis and Progress in the Soviet Economy

• Davies et al, The Economic Transformation of the Soviet Union

• Furst et al, Late Stalinist Russia

• Koktin, Magnetic Mountain

• Nove, An Economic History of the USSR

• Zaleski, Stalinist Planning for Economic Growth

To add (imperfectly) to the other fine answers, although the drab ugliness of Eastern bloc architecture might seem like a tool of social oppression, the reality behind the adaptation of prefabricated concrete was more prosaic. This architectural style was an expedient solution to a postwar housing crisis that at the time seemed to be modern.

The popular image of the Eastern bloc city is one of rebar and brutalist prefabricated architecture, but this was far from the only architectural style employed by the various Communist states. Soviet architecture in the era of NEP and early Stalinist periods was actually quite modern and progressive. The Zuyev Worker's Club is an example of this type of building embraced by the Constructivists of the early Soviet period. Late Stalinist architecture gravitated towards a monumentalist and excessive ornamentation, as exemplified by the Stalinist "Wedding Cake" style of the "Seven Sisters" Complex built in Moscow postwar.

The problem with both of these architectural approaches is that did not resolve the acute housing crisis of the 1930s and postwar period. In the latter case, not only did the war destroy much of the preexisting housing, but the drive towards implementing a centralized economy focused on industrialization created exacerbated the housing shortage. Urban planners and architects were under intense pressure from the state's authorities to resolve this housing crisis, hence there was an very little resistance to both prefabrication and concrete. Aesthetic concerns took second priority to resolving the housing shortage. This resulting use of extensive prefabrication built upon and expanded prewar concepts in urban design pioneered in the West during the Depression. The resulting Brutalist architectural style of the 1950s and 60s was both cheap, efficient, and alleviated the housing shortage. Looking beyond its stark concrete, these prefabricated housing did a much better job at creating a livable space with a modicum of privacy than prior Soviet attempts at mass housing such as the kommunalka (communal apartments). Many contemporaneous urban planners on both sides of the Iron Curtain saw Brutalism as a progressive and modern approach, which eased the Soviet adaptation of this style.

The problem with Brutalism and other ferro-concrete structures was that whatever their aesthetic charms, such as they exist, wore off with time. Rebar leached through the concrete, the large, flat concrete slabs handled inclement weather poorly, and their relative permanence made their destruction more labor-intensive than other dilapidated buildings. But the problem with replacing this style with a new form of housing in the Eastern bloc was that the once the planned economy was geared for the production of prefabricated concrete slab panels, it became an uphill battle for the state to produce different building types. Prefabrication was cheap, efficient, and available, which became highly attractive in the period of Brezhnev economic stagnation. The preponderance of Brutalist architecture ironically became a visual metaphor for Soviet stagnation as the West moved away from Brutalist architecture in favor of more aesthetically appealing designs.

Sources

Schlögel, Karl. Moscow. London: Reaktion, 2005.

Zarecor, Kimberly Elman. Manufacturing a Socialist Modernity Housing in Czechoslovakia, 1945-1960. Pittsburgh, Pa: University of Pittsburgh Press, 2011.

I'd look into Corbusier (I believe that's his name) the french atchitect that inspired very efficient box like housing seen in South and Central America (my region of study) during the cold war. The book radical cities details the architecture in social contexts...hope this helps!