You don't need to reinvent the justification, just quote straight from the "Resolution on eliminating excesses in design and construction" from the USSR, 1955 [0]:
The Central Committee of the CPSU and the Council of Ministers of the USSR resolutely condemn the mistakes made in architecture, design and construction, as contradicting the line of the Party and the Government in this matter, causing significant damage to the national economy and hindering the improvement of the housing and cultural and living conditions of workers.
When designing and constructing buildings and structures, architects and engineers must pay primary attention to issues of economics, construction, creating the greatest conveniences for the population, landscaping, apartments, schools, hospitals and other buildings and structures, as well as landscaping of residential areas and neighborhoods.
In order to avoid excesses and amateurishness, our architects and engineers must become conductors of everything new and progressive in design and construction. Construction must be carried out according to the most economical standard projects, developed taking into account the best achievements of domestic and foreign construction, based on industrial production methods.
Soviet architecture should be characterized by simplicity, strictness of forms and economy of solutions. The attractive appearance of a building and structure should be created not by using far-fetched, expensive decorative ornaments, but by organic connection of architectural forms with the purpose of buildings and structures, their good proportions, as well as the correct use of materials, structures and details and high quality of work.
The Central Committee of the CPSU and the Council of Ministers of the USSR believe that decisively overcoming shortcomings in design and construction, and the rapid and complete elimination of excesses in architecture will make it possible to save significant funds and direct them to the further expansion of housing, cultural and domestic, industrial and agricultural construction, as well as to the expansion of work on the improvement and landscaping of cities and towns.
That, incidentally, was the point of time when the Soviets borrowed the brutalism from the UK; it'd be only fair for the UK to re-embrace it. All in the name of the people's prosperity and happiness, and it worked so well in the past too! Oh, and also retroactively fine the most prominent architects for good measure as well, to set proper example.