Why should the USA be forced to do business with a communist dictatorship? Countries are free to trade or not with other countries as they choose. They're welcome to set up their own alternative financial systems and currencies. Not our problem.

The blame here is 100% on the Cuban government. If they want to improve conditions for their people then all they have to do is free the political prisoners, institute multi-party liberal democracy, and adopt free-market capitalism. If they took those simple steps then it would bring tremendous benefits to their country even if US sanctions remained in place.