- To prevent the fencing of American property stolen in post-revolutionary expropriations and give Cuba an incentive to give full compensation.
- To punish Cuba for the attack on unarmed airplanes in international airspace.
- To induce the Cuban people to overthrow the socialist regime.
Perhaps 2 and 3 are the same. Regardless, the embargo has been ineffective on all counts. It has not induced Cuba to compensate victims of the expropriation, nor has it induced regime change. One may argue that it has strengthened the socialist state, by giving it an alibi for its own failings. Consider the Castroist line the newest version of "Socialism is great in theory, it just hasn't been properly done yet.": "It isn't socialism that is causing mass deprivations, but rather the Yanqui bloqueado". Stupid, yes, but even a US Congressman, Jose Serrano from the Bronx, NY, has bought it. (Any Congressman mistaking the embargo for a blockade is not thinking critically and possibly taking his talking points from the Cuban socialists, leaving him unfit for office either way.)
Reasons for failure are complex; Europe's lack of solidarity, Cuban authoritarianism, and simple poverty are all possibilities.
The US has since learned that trade can subvert authoritarianism and socialism itself, as has been done in China, Vietnam, and (arguably) the social-democracies of Europe. Reform, be it democratizing or merely liberalising, does not change the fact that the Cuban government stole something, or rather billions of dollars worth of somethings.
Everyone in the world would be owed compensation by everyone else were all historic wrongs to be righted by transfer from one group of descendants to another. It would be ridiculous to require Mongolia to pay reparations to anyone who had ancestors in Poland, Hungary, or Damascus in the 1200s, or even for the USA to pay the descendants of United Empire Loyalists or descendants of slaveholders to pay descendants of slaves. Such claims are anhistorical inventions, in the case of slavery reparations, rediscovered generations later by those with a victim complex, and in the case of the Godfrey-Milliken Bill, childish jokes.
Claims that have been consistently pursued through the decades, with the struggle carried on--not invented--by heirs are a different matter, as are claims made by living victims. The call for a right of return and compensation for property expropriated under the Absentee Property Law from Arabs who fled fearing atrocities at the hands of militant Jewish nationalists is essentially legitimate and cannot be made otherwise by stalling tactics.
Inconsistency concerning Israel aside, this is the position of the United States, even toward Native American bands, like the Sioux, who have kept up the legal fight continuously. It is an extension of the common law rights of heirs to continue to pursue the civil claims of the decedent, and it is the policy of peace. Just as thieves must never be allowed to keep their gains, so too must conquest, by outside aggressors or socialist guerillas, never be allowed to yield permanent material gain.
Compensation to victims of expropriation is not currently being collected. Cuba refuses to even discuss the matter. Trade provides a means to collect: a surcharge of 20% on purchases of American goods or services made by the Cuban government (or its straw buyers) and 5% on purchases by Cuban private enterprise could be levied until victims are compensated with interest. The rate disparity is to shift the burden to the real perpetrators and to incentivize development of capitalism. Surely, Cuba can also trade with Europe, Mexico, Brazil, and others not imposing such a surcharge--as is already possible--but given its objection to the embargo, and that the USA is currently its primary food source, it's unlikely that it will completely forgo trade with the US. Note that any trade at all is an improvement from the status quo.
There's one catch: Article I Section 9 of the US Constitution prohibits export duties. Could a useful fiction (a la "socialism with Chinese characteristics" or the penumbra of an inkling of a whiff of a Constitutional right to privacy) be created to circumvent this? "This isn't an export duty, it's collection of restitution from Cuba."
Thinking of those pesky Europeans, lifting the embargo might just shut them up twice over. They could no longer blame the US for the misery of the Cuban, and might even become shamed by the truth; unlike the European's, the American's prejudices (Michael Moore excepted) will not lead him to be duped by Potemkin hospitals and hotels and silly UN metrics designed to reward countries with socialized healthcare. Strange as it seems, what would at first appear to be a softening might lead to long overdue international pressure on the socialists to liberalize, or at least to allow elections. Even if mere democratization is the result, Cuba is so socialist that votes can only take it in one direction.