How many times have you watched a martial arts class and thought to yourself "Nobody attacks like that in real life". Every one's defensive techniques looked great but the attacks themselves were lame at best. In real life, people often attack with wild abandonment - flailing arms, biting, kicking, eye gouging, tackling, etc.. Doesn't it make sense to train against these kinds of attacks? Of course it does.
Teaching a student how to attack his fellow student during training is perhaps one of the hardest parts of teaching the martial arts. Naturally, nobody wants to hurt each other in class but if you don't teach the student how to attack for real, the real damage will occur in the future, in the street when the stakes are much higher. Now this kind of attack training can start off slowly and the intensity can build as the students skill advances. But eventually the attacks must be full force or every one is just fooling themselves if they think that they will be able to defend themselves for real. Actual self-defense training is hard and it hurts. Anything else is aerobics.
Martial arts that are "sanitized for your protection" (which really means it is sanitized for the schools protection against being sued) should not be advertised as "self-defense". That would be false advertising. They should state that what they are teaching is a sport and nothing more. We all know that is usually not the case.
Next time you watch a martial art class, do not look at what the defender is doing but look at the attacker. Was the attack realistic?