Could you share an example of "today's actions are a continuation of these great deeds"? I do see USSR and even empire times nostalgy, but it is just a nostalgy, nothing else.
> They present bad things(imperialism) as good things. Today.
I don't see that happening. Since you state that this is a part of the state propaganda these ideas must be pretty widespread, but I cannot confirm that.
> It's like asking what's wrong with slavery or serfdom in the 19th century.
AFAIK in 19th century British empire dominated the world. So what? I don't quite get your idea of labeling 19th century imperialism bad. They could do better? Probably. It is meaninless to discuss this from a 21th century man's perspective.
> in a way that tells the audience that Russian/Soviet imperialism was a great thing
I would disagree. Soviet "imperialism" was always backwards, everybody was tooking advantage of it, except russians themselves.