Spoiler Alert: I am not an expert on anything having to do with Jewish Law. I went to yeshiva for elementary school, high school AND college and due to childbirth, age and probably plain old stupidity, I have no recollection of much of what I have learned...except if a cow falls into a ditch on my property, I am responsible for the cost of the cow. I also must confess that in college, I failed the course on the Sabbath, a "holiday" that I celebrate every week of my life. I failed it. And had to take an incomplete. There...it's all out in the open. Now you can take whatever I write with the grain of salt that it is worth.
Many orthodox women are unhappy with their role in the religion. I happen to be perfectly content with not having to pray three times a day(though I still get credit for making sure my boys get there), with not having to read from the Torah and many other rules the men are "required" to do. The orthodox view on homosexuality upsets me. We are supposed to be a welcoming religion, not one that ostracizes. The orthodox view on abortion upsets me. And yet, I continue to be a part of this branch of the religion because there are things that are beautiful about it and it is a tradition that has been passed down to me. I don't always agree with husband #1 on the rigidity of it. There are things we just can't question, even if the questions are endless...
If there are young women who have taken on the responsibility(not sure that is the correct word, but, again, I am not an expert on anything, except for maybe snack foods) of putting tefillin on, either because it is something they have decided on their own, or their families have a tradition of doing so, good for them. They aren't asking to pray on the men's side of the mechitza, they aren't asking for a female circumcision, they are asking to continue doing something that has become the norm for them. They are not doing it by rote, like so many boys do....they are doing it because they want to, this is how they choose to celebrate their religion(i am just assuming this, again, I know nothing) And I applaud the principal who allowed them to do so.
We all have our opinions. We all can agree to disagree. That is what makes life interesting.