Just to mention it, attacking a politician on his or her private life isn´t that common or popular in Germany.

You´ve got Brandt, Schroeder, Fischer or Wulff as examples. Trying to use the private life of a politician against him always involves the risk of a back-lash.
That´s why most media won´t use that knowledge.

What do I care about their private life?
Are they competent or not?

Also, consider the case of Ole von Beust. Conservative CDU politician. As far as I can make it out, his father outed him unintentionally in an interview. Just like Wowereit according to your search. :)
And his popularity soared after he fired Schill allegedly trying to blackmail him.

And to say the truth if I didn´t follow the news seriously I doubt that I would know that von Beust or Westerwelle are gay. It´s just not a page 1 story.
Different to Wowereit, I admit. But only because of his "Und das is gut so" comment.