Instead of judging, maybe you're the one who should try using your brain?
The reason loads of people are electing for the daughter not to take self-defence classes is probably because it's mentioned in passing a couple times, and the choice to do so seems like an optional choice. Which it is, had it not been for the fact that it leads to defeat an hour later. It's a bad design on the part of the game's creator. It's so bad they think that can't possibly be the way to solve the issue. After all, that choice was made out to seem completely voluntary.
To make matters worse, the concept of daughter being this naive, dependent and good looking girl is more or less contradicted by self-defence classes, which is about being an independent badass. So, for a lot of people who find the premise of the game hot, they will want precisely not to make the choice of taking those classes.
That is why you have loads of people running into this problem.