The problem is that the US never really let Cuba devellop as it should have.
The embargo considering that Cuba is at the doorstep of one of the
biggest trading powers really made the economy disfunctional for a long time.
Funny enough, its when the USSR stopped helping Cuba that it started
to really form an identity of its own economically.
Repression is real, but also a reaction to the siege mentality, who knows
if Castro would have had such tight reign if the US would have been more benign.
In 1959, Castro was quite open to having cordial relationship with the US, its
only when he was rebuffed that he started turning towards the USSR which during the
depth of the cold war was almost like a declaration of war towards the US. The
rich cuban ruling class, which where ruling as kings with little regards for
most of the population, which had been kicked off their properties provided
the electoral base which would skew florida politics for the 40 years to come.
Then, the bay of pig incident happened which cemented these tense relations
happened in 1961 and then Castro made his biggest mistake, with letting the USSR
install missiles, which was the perfect excuse for the embargo.
When you compare Cuba to China or the Saudi's or countless other dictatorships
the US has supported or traded with actively, the level of oppression seems
run of the mill to mild (if such an evaluation can be made with oppression... >

).
So, its not dictatorships that makes the embargo lasts, but the political
clout of the southern florida latinos.
Of the revolutionary, he's possibly one of the least flawed! But, that's
not saying much considering the others :-).