I think it is worth remembering that it wasn't just sexual assaults. One girl was nearly set on fire after someone shoved a lit firework into her hoodie. She has suffered severe burns on her neck and shoulders.
It seems that, in certain political and media circles, the well-being of unknown male foreign nationals is more important than the safety and security of female citizens.
And, yes, I do believe there is a willful, race-induced blindness at play here, along with the prejudices of certain stereotypes. Had the recent migrant flows across Europe been spawned by a civil war in Russia and we had seen large numbers of non-Russian male foreign nationals using the conflict to claim asylum in Europe among the exodus, and the Cologne incident then been committed by "Russian and Slavic-looking" young men, speaking a "Russian-type" language, I suspect the political and media reaction would have been very different.