One of the things I love about FRC is that teams have the freedom to be run they way the team wants to be run. Teams frequently choose some direction that will both help and hinder them in some aspect. The all boy/girl teams are one of these choices. Having a single sex team has benefits, but it is also unrealistic for the working world (other than some very specific instances). I think you can make a comparison to a team deciding to CNC EVERY part versus a team that decides to HAND CRAFT every part. You will learn very different skill sets from both of those choices. Both skill sets are valuable, and both will allow you to be better and gain additional depth in the particular area. This depth though comes at a cost of breadth.
All girls teams (by choice) are a tool that can be used to promote involvement, just like FRC is a tool to promote STEM involvement. FRC takes the most fun and exciting elements of a technical career and lumps it into a fun competition.
Why remove the option of a tool? That would be as ridiculous as not allowing a perfectly good (an readily available) switch to be used in a minibot.
All "anything" (girl/boy/CNC/Hand Crafted/Plastic/Wood/...) teams should have an open discussion that their decision to go that direction will likely have some detractors, and they should be aware of the PROs/CONs of their choice.
********Women Rockstars************************
I am a bit surprised no one has mentioned Kyle Hughes in this thread. She is the team lead for 27 and a WFA winner. She has also been included in Kickoff videos and panels.
Kyle is definitely one of the "Rockstars" of FRC.
http://www.teamrush27.net/whoweare/mentors.html