That's the problem...he was "seen" as highly useful, but what useful intelligence did he actually provide this country, in order to overlook the fact that he was a freaking monster? We'll never know, because the government will never allow us to know what any of these monsters they coddled, actually did to defeat the Russians, and communism.
It wasn't until 1989 that the Berlin Wall fell, and 1991, when the U.S.S.R. collapsed. Ronald Reagan, and his policies had more to do with defeating the U.S.S.R. than any crap intelligence these animals provided our intelligence agencies in the previous 40 years. And it didn't stop the eventual spread of communism to this country. All we know is what the CIA and the other agencies have fed us over the years, and you know they would never tell us the truth about any of it.
As for the CIA's effectiveness in the latter stages of the Cold War, in time, internal intelligence documents and studies get released that allow a qualified assessment. As it happens, under Bill Casey and his successors under Reagan and Bush, the CIA did a fairly good job of helping bring down the USSR.
Most notably, the CIA provided arms to the Afghan resistance and cash and other resources to sustain the anticommunist Solidarity movement in Poland. The CIA also recruited a highly placed Polish military officer, Ryszard Kukliński, whose reporting from 1972 to 1981 yielded 35,000 pages of mostly Soviet secret documents. This provided the US and NATO with an edge in assessing and countering Soviet military readiness and capabilities.
According to Carter's National Security Adviser, Zbigniew Brzeziński, "Kukliński's information permitted us to make counterplans to disrupt command-and-control facilities rather than only relying on a massive counterattack on forward positions, which would have hit Poland."
Like some of the best spies, Kuklinski had a good record and acted from patriotic and moral principles. He and his wife and two sons were exfiltrated by the CIA in late 1981. Kukliński died in a hospital in Tampa in 2004. His remains were eventually repatriated to Poland and reinterred with honors in a military cemetery.
There is a great deal that we do not know, but Congressional oversight seems mostly satisfied that the US gets sufficient value for the cost to maintain the CIA and other spy agencies.