This is another of those Wilsonian holdover bad things we do. Before Woodrow Wilson, we recognized the de facto government, that is the government that had control of the country. This was the realistic diplomacy that we had under cool-thinking officials.
Then we had Woodrow Wilson and the moralistic approach and we never escaped that. George W. Bush seems to be channeling Woody.
We should have relations with every country in the world whether we love it or not. That goes for left, right and in the middle governments or dictators.
Another reason we keep up this ridiculous embargo is because of the JFK embarrassment over the Bay of Pigs fiasco that he perpetrated. He had to try to get even, hence the embargo. We would have dropped this dumb idea long ago except we are being "true" to the "sacred memory" of Kennedy. Laughable.