Earlier quoted context omitted.
But they simply weren't able to sustain it. In the West, while the military industry initially pushed computer development, private companies quickly adapted those technologies for the consumer market. Over time, the Western consumer market became vastly larger than the military one. In the USSR, this cross-pollination wasn't possible because anything that even touched the military was immediately classified as a sta…
I think it's a bit different. USSR just wasn't rich enough to afford experimentation and innovation. Resources (including human brain power) were quite limited. So they had to copy proven solutions. Simple as that. It's easy to judge them in the retrospective. But they had to make decisions, using the information the had at the moment, weighing risks as they saw them at that moment.
Even accepting the counter-narrative that the story of Tetris was "evil" capitalists taking advantage of the USSR to "steal" Tetris from the people of the USSR and the output of their socialist labor, the USSR was never in the position to offer Tetris to every worker in the country as a gift for their hard work because it was a state secret and computing wasn't something everyone had access to.
It is interesting to ponder if the USSR had made different decisions on the usefulness of general computing for the masses rather than the military what would have happened to Tetris as one interesting microcosm of the USSR's relationship to computing.