Like Devil said, if I were teaching short term self defense (in fact, I am, to my girlfriend right now), the curriculum would be quite a bit different.
Seriously though, bear in mind that this is a manual for training soldiers for World War II, where US and Britain had to train a huge number of people who had never been in a fight in their whole lives to have some kind of combat capability in the shortest amount of time as possible. Therefore the ease of learning/training in the methods trumps the effectiveness of the said techniques (not that the latter is not important). If you look carefully there are techniques in the manual that Fairbairn admits "has only one in two chance of success" or even "one in ten chance of success". This is a manual designed to maximise a person's rate of survival with a month or two's group training, not to train people into combat specialists.