I'm from Romania, another former communist country from the Eastern block.
First of all you are comparing third world countries like Chile or El Salvador with European countries that were doing well before WWII. At least Romania was. This makes your comparison flawed, because when a country is somewhat rich, with a working middle class, with somewhat working institutions, it does have the resources to spare and it will still be doing OK.
Because of the Molotov–Ribbentrop pact between Hitler and Stalin, we've lost territories like Bessarabia and Northern Bukovina to the Soviet Union, by force of course. And I must say that this was happening in 1940, with a Romania that hadn't entered the war yet. Russians later blamed us for giving support to the Germans on their invasion, but that's why they say you reap what you sow. Bessarabia is now the republic of Moldova. We still think of them as being Bessarabia, as Moldova is also the name of the adjacent region in Romania.
After the war, the soviet induced famine has hit us as well, but it hit Moldavians much harder. Hundreds of thousands of people have died of hunger and the official numbers are actually lower than what happened (my grandfather lived to tell me the story). But furthermore, we had to pay war reparations. And during their invasion on our territory, they've established what are called Sovroms, which were enterprises meant to deplete the resources of our country, with the effect that we've paid much, much more than the war reparations that were demanded. The soviets also mined us, for example we've shipped thousands of tons of uranium ore which ended up being used in their atomic bomb project.
In Bessarabia and Northern Bukovina the soviets did what Russians do best when invading a territory. They arrested, executed or deported to labour camps in Siberia hundreds of thousands of people and they also planted Russians on those territories, with the purpose of completely destroying their national identity. And this strategy of theirs does wonders. In the eyes of many Moldavians, the Russians are their "brothers" and Romania has had a "colonial policy" that has to be terminated. In return we've started granting them dual citizenship that has been their gate to the EU. We wouldn't have any economic benefit in an eventual unification of course, the difference between Romania and the Republic of Moldova being the difference between western and eastern Germany in the eighties. This is why Ukraine is so divided btw, as this is their usual modus operandi and anybody that says Russia's actions there are justified is either an ignorant or full of shit.
But back to the soviets, in Romania the result was poverty of course. But as a fun fact, even our former communist government was anti-Russian. For example at some point under Ceaușescu we declined to place our military forces under the Warsaw Pact's joint command and we also refused to increase our military expenditures. We also refused to side with Russia on several political conflicts. And Romania was actually isolated from the rest of the Eastern block. We were the pariah of the Warsaw Pact. Our neighbors had it easier.
But by far the biggest damage that the soviets did to us is the mentality, which is the cause for the corrupted system we've inherited after the communist block fell. We've been recovering quite well, but it's far from over, being much like cancer extirpation. And while our brethren from around our country are sometimes giving signs of missing the USSR, we don't. In fact that's the reason I'm proud of my country - we've always been at the intersection of empires, we're still here, we're still speaking a romance language and we hate everybody :-)