Well the thing about attacks is that you usually can't run from them effectively so you have to deal with them. In many respects the "rule of 21" applies for most women that are attacked.
This is simply incorrect. If you are preaching this then you are putting anybody who listens to you in danger unnecessarily. You are talking about some kind of fantasy attack situation which is incredibly rare, fairly avoidable and if it should ever come to it, would not be prevented by any self-defense technique that she can learn without putting the woman in more danger than it prevents. Let's talk for a second about rape/sexual assault, since this is very woman-specific. Well, let's talk statistics for a moment: the vast majority of rapes are acquaintance rapes (80% or so). You are talking about a cornered woman where the man has "closed on her", when four out of five attacks do not happen in any way even approaching the fantasy that you have in mind. The fact is that most rape situations are escapable, as long as
A) The woman realizes that she is in danger early
B) She is determined to escape the danger
C) She does not feel compelled to handle the situation on her own
If there is only one thing that women should be taught in self-protection it is situational awareness: recognizing when you are in danger so you can escape it. This is really, really obvious when you consider acquaintance rape. The situation is not sudden, it is a process leading up to the attack. Whether the process takes minutes or months, the situation is not out-of-the-blue. The warning signs are there, but they are not seen, ignored or the woman decides to try to handle it on her own.
Even in stranger-rape, situational awareness will get a woman out of the vast majority of scenarios. This is because rape cannot happen when there are other people around. This means that if a woman can "call in the cavalry", the possibility of an attack all but disappears. A rapist who tries to "ply his trade" in the middle of a crowd will be dragged off and strung up by his testicles in short order. No criminal (unless he is absolutely insane) is even going to attempt this and the attack would fail anyway. Women should be taught to identify potentially dangerous situations and act on them: if she is entering an area where help is out of earshot or more than 30s away, where a single person or a group is loitering she is in real danger. More importantly, women should be taught not to ignore the alarm bells and red flags when they are going off. Somewhat more surprising is that this even needs to be said. You'd really be surprised how many victims knew that something wrong with a situation and walked into it anyway, assuming that everything would just sort itself out. If you feel uneasy walking into a mostly-deserted parking lot, then don't! Turn back and get back to a crowd. The false confidence she can simply deal with an attack on her own if it happens is actually a real danger to the woman here.
Now let's humor your incredibly hypothetical jump-out-of-the-bushes cornered stranger attack scenario. You are suggesting that in such situations the advisable tactic is to attempt to out-viscious, out-anger or out-technique such an attacker (the only possible ways you could realistically have an advantage). Well, let's look at such an attacker for a second. Nobody, short of being completely deranged willingly initiates violence if he believes that there is a possibility he could lose. In his mind he will be holding all the cards, because he is either very big and strong, heavily armed, unbelievably sadistic and viscious or with a group of friends. Mostly likely some combination of all the above. In such a situation, you will be facing incredibly bad odds. Not a single unarmed attacker. Not a weak little guy making a feeble attempt to grab you. A group of big strong mean guys holding knives. Picture that for a second and try to imagine a small woman using her Aikido/Jujitsu/Karate/Wing Chun skills to successfully fight them off. The goal of such an attacker is not to fight with you, it is to overwhelm you. If there is a way for such an attacker to gain an advantage, he will be using it.
Teaching women skills that will only help them if they have somehow managed to get themselves cornered (in a way that probably wouldn't have happened if her situational awareness were better) by a stupid and completely incompetent attacker does not strike me as a valuable thing to do. Far from being common as you suggest, these attacks simply do not tend to happen. Telling women that what you are teaching will keep them safe in such a situation might have the benefit of giving them confidence and making them feel empowered, but God help them if they ever really get attacked.