How can someone find "Bridges in Athens" if the category title was written in Greek? Or "Palaces in Istambul"? Or "Rivers in India" (and what alphabet should we use in this last case?).
Categories redirect works quite well, so this argument is not valid. See for example http://commons.wikimedia.org/wiki/Category:Monte_Bianco
Yes, you can redirect people. But you can't redirect images. Hence people will not find images that are not in the "deutsch name" gallery.
Furthermore, I object that this is made some kind of political/ideological issue. I speak a language that is not in the top 100 of most spoken languages in the world, which is not the case for most of you. I've also studied 14 foreign languages (no, I don't know most of them). Neither of these nor both of them combined stops me from seeing that the lingua franca (sic!) is English and using the most common language is the only practical solution.