I think a lot of CS departments would be happy to aim at 50/50 gender parity, if their application pipeline were anywhere near close enough to support it. When applicant ratios are in the range of 90% male, it's very hard to get more than 20-30% women in the incoming class, even if you really go out of your way to aim at gender balance.
It took med schools a few decades too, over which they first removed overt barriers (like "medicine isn't for women" attitudes among faculty), then successfully convinced more women to apply, and then finally accepted many of those applying women. CS's troubles are complex, but I think one of the stickiest ones is that interest/disinterest in studying CS seems to develop around high-school (same as studying math), so the imbalance somehow has to be addressed at the pre-university level. Med-school doesn't seem to have the same differentiate-by-age-15 aspect.
It took med schools a few decades too, over which they first removed overt barriers (like "medicine isn't for women" attitudes among faculty), then successfully convinced more women to apply, and then finally accepted many of those applying women. CS's troubles are complex, but I think one of the stickiest ones is that interest/disinterest in studying CS seems to develop around high-school (same as studying math), so the imbalance somehow has to be addressed at the pre-university level. Med-school doesn't seem to have the same differentiate-by-age-15 aspect.