I think that it would be okay for a person to change their citizenship, if they want to move off to a separate country. They need to make sure that the other country does not care that they are coming, and need to make sure that they have the money.
We don't get to choose where we are born, do we? Well, in many cases people are not very happy where they were born, or they may have other valid reasons for moving. Citizenship should not be a life sentence. People should be free to choose and free to move (legally, of course).
If you are born in one country but would prefer to live in another, I don't see anything wrong with changing your citizenship (following that country's specific requirements). Simply being born in a particular country should not force you to live in that same country and abide by its rules forever.
I do not think that a person who decides to change their citizenship is necessarily somebody to be criticized. Sometimes, some people are just born into a country, and really have no say in it. It is a fair way for somebody who finds another country they want to associate with and live at later in life.
If someone feels more at home in a country other than the country of his birth, more in tune with the values or culture of another country, let him change his citizenship. Why should an accident of birth determine your country for your whole life? You can decide where in the world you want to live; you should become a full citizen, with all the voting rights and privileges, of any country you choose.