Folks, keep in mind that the motions to dismiss the charges being discussed here were made by the defense attorneys for the accused. These are professionals who are doing their jobs, the jobs our country mandates be done. Aggressively.
I've done defense work. I can best liken it to being the single gladiator that society provides to someone whom the rest of us would like to see torn apart by lions. Out you go with sword and armor to fight for this person. And it is not a show defense. You fight to kill. You raise and pursue everything you legitimately can - irrespective of whether the crowd is yet further ouraged.
I don't have a problem with the defense attorney raising the issue. As you say, it's their job. In fact, I WANT the defense attorney to make me prove my case with a vigorous defense on the facts -- because I never want to find out that, as a result of my investigation, an innocent person got convicted.
But I do think there's enough given here for the case to move to trial, criminally. Let the case be tried; consider this sort of issue upon conviction. The judge or jury, as trier of fact, can determine whether or not the girls did commit the assault alleged, and also whether there was justification. Then, if they are convicted, issues of home life, emotional problems, etc. can be examined in mitigation of sentence.