User blog comment:Darkcloud1111/Good Idea, Bad Idea-Best Day Ever/@comment-10380701-20140726023432/@comment-2006510-20140726023947

I believe that, aside from a number of the larger ones, they AREN'T as big a threat as implied. They WERE at the beginning, but when humans harnessed Dust, things went downhill for the Grimm.

This is why they seem like cannon fodder, and the bigger ones are bosses, but the real threats are the human ones who undermine the 'points of light' they've worked so hard to establish in a sea of darkness.

And besides, Grimm don't have souls, and hence no Aura - but humans do