In my personal view, this is predominantly a product of the key underpinnings of German political culture in the postwar era. During the Interbellum and World War II, political radicalism was extremely pervasive on both the far left and far right.

During Hitler's rise to power in the late 1920s and early 1930s, German socialists and communists became increasingly marginalised as they lost most of their urban-industrial powerbase in the electorate to Nazi repression, and conservative-government based suppression. Many high-profile social democrats and communists from the 1930s therefore chose exile over execution, and left the country for foreign shores. Social democrats and the less-dogmatic communists tended to end up in intellectual left-wing circles in France, Republican Spain, Mexico, the USA, and the United Kingdom, whereas the original hardliners turned to the Soviet Union for refuge.

Notable figures that left Germany during the political turmoil of the 1930s are Wilhelm Pieck, Walter Ulbricht, and Erich Honecker. Pieck and Ulbricht became important figures in the post-1949 era East Germany as heads of state and high-profile political functionaries, as part of the Soviet's maintenance of it's sphere of influence in East-Central Europe.

Honecker is also interesting, as he went to complete a school programme by 1931 in the Soviet Union, and afterwards returned to Germany as political agitator. Honecker - with many concurrent Warsaw Pact political leaders - became part of a wide transnational circle of so-called 'Moscow Communists' that were installed by the Soviet Union in their respective countries of origin as mid-level political activists, agitators - and later in the 1970s - as political elites.

Now, beyond this it is also notable that East Germany did relatively well for itself as satellite-state of the Soviet Union in economic terms, leaving political security as a major issue, in part due to the emergence of a semi-agent materialistic middle class, and the state attempts at achieving this.

Finally, at some point the orthodoxy of East Germany in political terms became something of a self-fulfilling prophecy. Neighbouring states (and their political establishments) did frequently and implicitly criticise the East Germans for their 'Holier than Thou' attitude to ideology and international politics.

All this, and more, drawn from:

Applebaum, Anne. Iron Curtain: The Crushing of Eastern Europe 1944-56 (London: Penguin Group, 2012)

Beevor, Antony. The Battle for Spain (London: Orion Publishing, 2007)

Blumenthal-Barby, Martin. “A ‘Vital Feeling’ of ‘Humanist Hatred’: Narratives of Sovereignty and Totalitarian Childhoods” in Journal of Contemporary Central and Eastern Europe 15, No.1 (2007): pp. 65-86

Formisano, Ronald P., “The Concept of Political Culture” in The Journal of Interdisciplinary History 31, No. 3 (2001): pp. 393–426

Judt, Tony. Postwar: A History of Europe since 1945 (London: Penguin, 2005)

Mazower, Mark. Dark Continent – Europe’s Twentieth Century (London: Allen Lane, 1998)

Payne, Stanley G. Civil War in Europe, 1905-1949 (Cambridge: Cambridge University Press, 2011)

Péteri, Györgi. “Nylon Curtain: Transnational and Transsystemic Tendencies In the Cultural Life of State-Socialist Russia and East-Central Europe” in Slavonica 10, No. 2 (2004): pp. 114-123