So it is not illegal? you just need to go through the proper bureaucracy as you do with every countries. Last I looked into it a few years back it was easy to get the paper work, one person I found who went there just signed up for guitar lessons in Havana to study Cuban guitar, showed the paperwork for the guitar classes and was good to go because it was for educational reasons even if the guitar lessons only accounted for a tiny portion of their time there. The white listed reasons are fairly broad and easy to work within, sure you can't just hop on a plane for a weekend visit but that is true of many countries that no one would say it is illegal to go to.