I think you're mixing the question of what creates great mathematics department and what makes a region generally interesting (plus the article actually answers

I think you're mixing the question of what creates great mathematics department and what makes a region generally interesting (plus the article actually answers all those questions well as other commenters note). Germany has many great mathematicians at present. Just by expanding population and budgets, it probably has more great mathematicians than in the Göttingen days. These mathematicians are not as famous as the Göttingeners of the 1920s, however, fundamentally because earlier mathematicians laid the foundation of the field and later researchers basically have built on those foundations and can't claim the same glory. As to post-war Germany being boring - I'd assume but it seem neither here nor there.