I just would like to point out no state in history has actually achieved communism. They have all been socialist totalitarian believing they are on the road to full communism and the elimination of the State itself.
This whole monument and debate is
esoteric and needless.
So is communism bad? I'm not sure I would say yes- but history has shown that, the mechanics of achieving a of communist society perverses into totalitarianism. Totalitarianism you- I- could make a concrete statement saying is without question bad. But you can have a totalitarian state that is capitalist or communist.
The theory of communism comes from Marx writing (and others before him) in the 19th century but it was in the 20th century, about ~40 years after his death and ~100 years after his birth, before we saw the first States arise with the goal of implementing a communist society. Currently only Cuba and N.Korea could be called "Communist", though still only socialist. China is more neo-fascist then communist.
That being said-
capitalism, all though raising the standard of living for 100s of millions faster than any other system in human history has some serious flaws. One being it relies on the rampant destruction and privatization of the "commons"- like the environment and air we breath. So fast forward a 100 years to 2115 children might not be viewing the current age of rampant and
accelerating capitalist global consumerism as a good thing. (If we are still on this planet-
yes, that is a
very real possibility.)
See how needless and esoteric this whole thing is?
lol
TLDR. We should have no monument but if we are going to build a monument it should be to the victims of Totalitarianism. Actually, the holocaust and monument to the victims of totalitarianism could share the same grounds, as they are one and the same.