It is the old Stiglitz vs. Friedman issue which emerged after the fall of the Soviet Union, Friedman thought that you just have to create free markets and everything else will solve itself whereas Stiglitz pointed out that you first gotta establish the rules and then privatize. Before Friedman died he admitted to Stiglitz that he was wrong.
I don't disagree with your analysis, the nationalist sentiments on both sides were too large and the right was too opportunistic. But the left was right, a slower unification would have been better.
This plus my lack of patriotism and, as you pointed out, the typical German grumpiness (you Mediterranean guys just know better how to enjoy life
) the reason I don't celebrate. A few years after the unification we had a pogrom in the East which was politically tolerated (police was slowed down) and the same opportunistic politicians used these sentiments to enforce tougher laws on political asylum.
This is why I have my problems with following the mood of the public. It is not merely not standing in the tradition of the Enlightenment but also leading to catastrophes. I rather want politicians who have the balls to not be populist and do the right thing even though it is unpopular.