For me people have the right to choose their retirement place, a place where they can enjoy their life and become comfortable in their retirement years. You wouldn't know unless you live in that country for a certain period of time before making a decision. Some people will fall in love with the place when they live in another country therefore will decide to live there permanently.
It is definitely your advantage if you live in a country with lower cost of living and decent medical cost. But it shouldn't be the main reason why you have to move in a different country. First you must like or love the country and the people. Even if you don't have money problem but you don't like the country and the people and you don't feel safe living there, then there is no point in retiring there isn't it?