Not entirely true re: Soviets. While many wanted a glorious technocratic future, many were won over by tales of how it would be just as great as under Peter. People remember despots fondly, generally, and Russians very definitely believe in the gilded age of Russia, and that it was glorious for all. They forget about the serfdom bit.

Re Germany, Aryanism.

And now russians see Stalin age as the golden one, although they don't forget about Gulag and political repressions: instead, they wholeheartedly approve them, just as they did when it happened.

Correct. This is rather why the glorious past is such a dangerous fallacy - they see the artefacts and remnants of regimes that specialises in propaganda, and mistake it for reality. The same happens within minds as it does in the external world - rose-tinted glasses - and so the cycle repeats.

I honestly don't know if we're up to escaping it. We are beautifully fallible and flawed - without, we would not have art and love and all that is good, so we must take the bad with, lest we lose what it is to be human.