What is most impressive is the limited budget and resources they had. The US spent trillions in today's money on their space programme just to compete.
Not really. The entire country (and the union of countries) was one big military factory. Remember, planned economy, so every engineer of a certain grade gets paid the same amount of money. How convenient this is, you have to work, otherwise you go to jail, and if you do work, you can't get competitive salary. It was not a lot of money either, but it was for the best, there is no consumer stuff to buy anyway. Who needs vacuum cleaners and refrigerators if we are building rockets and communism?
Also, the price of failure in the US was being fired or demoted, the price of failure in the USSR on high level project was being sent to Siberia (or reassigned to a new work place, as they were saying). And you could not really pick a place where to live in the USSR, after getting your degree, you were assigned to a certain factory, where you work for the rest of your life.
I'm not denying, there were some brilliant people out there, but saying that they did not spend a lot of money is not correct, they basically sold the country for that achievement.
And also, the reason why all those things are so well-designed, is that designers knew that they will be built by a bunch of drunk idiots, who don't give a s**t. So everything is over-engineered, because if rocket fails, an assembly line worker, who did not feel like using a torque wrench that day, will not get blamed, but designers will.