What planet are you from? The dive training industry is set up on more classes. You take basic open water, then before you are done they want to sign you up for advanced. Then rescue, then a bunch of specialties, some more beneficial than others. Many of these classes plug holes in the training.
The method of training that's most often employed by instructors today is very limited; as it doesn't try to improve a student's in-water ability (teaching the basics of equipment operation), fitness, or confidence (what part of today's diver training program causes a student to works-up a sweat or greatly increase stress?) Generally speaking the course is designed to be 'fun' (which is all fine and good). The goal is to prepare the student for ideal conditions where nothing is expected to go wrong. If this wasn't the case, it would be reflected in the Standards. The diver can enjoy looking at the fish in shallow warm water.
Panic kills divers. Although it can't be eliminated, it can be mitigated through training. The course content however is not currently within today's training programs. If instructor's are not trained to deal with panic themselves, how can they train others? This just isn't a requirement.
As long as nothing goes bump in the night, everything's fine. When it does however, the diver often becomes a victim of today's lower training Standards. That said, equipment is reliable and more people can share in the underwater experience. Most are not die hard divers that would benefit from more inclusive training. For those that want it, that could be a problem...
Regardless of the training program a diver requires experience to broaden the scope of his diving education. He needs to dive...