For at least 35 years, the U.S. embargo on diplomatic or commercial dealings with Cuba has been the single stupidest aspect of U.S. foreign policy.
Not the most destructive: that title would go to the decision to invade Iraq, plus the ongoing ramifications of the age of torture, open-ended war, and the security/surveillance state.
But the Cuba policy has been the stupidest, because there have been absolutely zero rational arguments for its strategic wisdom or tactical effectiveness. Jeffrey Goldberg, who has traveled in Cuba and interviewed Castro, more tactfully calls it "ridiculous." In my impetuous youth a few years ago, I called it not the stupidest part of U.S. policy but the "most idiotic." Take your pick.
I choose "at least 35 years" as the demarcation point for undeniable irrationality because that is when the U.S. fully normalized its relations with mainland China. If successive Republican and Democratic administrations could see the merit of trying to engage (rather than exclude) a one-party repressive communist-run state, even when that state had four times as many people as the U.S. did, and is nuclear-armed, and is a regional rival of several U.S. allies, how much more obvious is the case for a tiny little island practically within eyesight of the American mainland and certain to fall under the sway of U.S. cultural and economic influence if given a chance?
Not to mention that recognizing the People's Republic of China meant cutting off America's relationship with the people and government of the Republic of China on Taiwan, which itself has twice the population of Cuba and nearly 10 times as large an economy. There is no comparable tit-for-tat cost for the U.S. in normalizing relations with Cuba. As shown by the photo above, there are protests in Little Havana today. That is nothing compared with the riots in Taiwan after the U.S. announcement, which Warren Christopher braved when traveling there in 1978 to deliver the official news that the U.S. no longer considered Taiwan a real country.
The stupid policy persisted because of inertia, and because there actually was a counterpart to the Cold War-era "China Lobby" that pressured against dealing with Mao's Beijing government and in favor of Chiang Kai-Shek's Taiwan. This was of course the emigre Cuban community concentrated in Florida. Let's round up to say that perhaps 1 percent of the U.S. population has modern family ties to Cuba. That's not many people. But enough members of that 1 percent would work hard enough, in a concentrated enough political sphere, with enough resources and intensity behind them, that they were able, NRA-style, to make this a line just not worth crossing for most politicians. Very few members of the remaining 99 percent of the electorate were going to switch their votes based on Cuba policy. Why should politicians take the risk of infuriating the minority that cared?
Thus even though people out of electoral office—Richard Nixon as an ex-president, William F. Buckley, even (bravely!) Paul Ryan before his vice-presidential run—have urged opening up to Cuba, for people in office, or considering a run, the ramifications in Florida have made such a move not worth the risk and bother. Every sane person knew the Cuba policy "would" and "should" change. But it didn't.
Until now. It is unwholesome for U.S. democracy that so little now happens through normal "bill becomes a law" procedure, and so much depends on executive action. But in this case the executive is doing manifestly the right thing. Congratulations, thanks, and it's about time. "Don't do stupid shit" may have limits as a worldview, but it is an improvement over continuing a path of folly.