Have I got this right? You can travel to a country you are technically still at war with, but you can't travel to Cuba.
Actually,
as this article states, there are a few ways you can actually apply through the Treasury Department to gain permission to travel to Cuba. The last one they state in the article is the embargo-flouting plane ride from another country to Cuba. I know last year hip-hop and pop artists Jay-Z and Beyonce actually used one of those reasons to gain permission to go to Cuba.