Ilya Somin at Volokh Conspiracy has some thoughts:
First and foremost, Cold War-era Berlin was the most visible demonstration of the superiority of capitalism and democracy over communism and dictatorship. Despite the fact that East Germany had one of the highest standards of living in the Soviet bloc, it had to build a wall to keep its people from fleeing to the capitalist West. By contrast, West Germans and other westerners were free to move to the communist world anytime they wanted. Yet only a tiny handful ever did so. Decisions to “vote with your feet” are often even better indicators of peoples’ true preferences than ballot box voting, since foot voters have better incentives to become well-informed about the alternatives before them. Even more powerful evidence is the reality that many East Germans and others fled from communism even when doing so meant risking their lives.