This is such a difficult topic. When I started my undergraduate in CompSci, the department of 300 students had exactly 3 women. The faculty had way more female instructors than it did students. The Commucation Sciences department, which was on the same campus, had the inverse student population.
I'm all in favour for letting students making their own study (and career) choices, but when the imbalance is this great, I can't but help think that valuable perspectives are lost. And that's just looking at the sexes, that doesn't even take into account what could be gained from interacting with folks with different socio-economic backgrounds, who were equally underrepresented.
Trying to keep barriers for entry low seems worth while. Organizations which help people break into non-traditional fields (for their background/sex/whatever) also seem to be worth while. Funding them seems like a no brainer. This isn't limited to girls in tech. Also boys in nursing, poor kids in law school, brown kids in politics, whatever.