There is, of course, a deep divide between folks who argue that deeper structural dynamics drive events or the quirks of personalities and accidents of history make the difference. While it is clearer now that poor communication and such produced the focal point in time and space, the fact that large numbers of people rallied to the wall and the gates suggests something more than an accident. But I am not an expert on intra-German politics. A year in the Pentagon did teach me that personalities and arcane procedures do matter, more than I wanted to believe.
Either way, these stories are quite intriguing. And the NY Times story linked above largely asserts reunification worked pretty well, especially given how different the two parts of Germany were economically. So, perhaps we ought not jump all over Germany for the restrictions on their forces in Afghanistan.
And it is fun to remember people's fears in 1989:
The reality of Germany today makes it difficult to remember the immediate concerns in Europe after the wall fell. Leaders like President François Mitterrand of France and, in particular, Prime Minister Margaret Thatcher of Britain, worried aloud that a reunified Germany was likely to drift away from the NATO alliance and the structures of the European Union and at worst might return to the path of extreme nationalism.
See Fred Kaplan on why Berlin mattered.