As a new diver, I will give my perspective. I took a 3 day course where the first day was a discover dive, the second day was the pool dives and the theory, and the third day was the final ow dives. Basically all of my theoretical training took place in one afternoon--4 hours. In retrospect I don't think there is anyway someone can get the proper training in 4 hours.
My observation is that there are 2 classes of divers out there--the well trained totally independant divers, and the half assed trained semi independant divers.My experience is many of the dive shops look at divers this way already. If someone comes in to their shop who they suspect is new or shaky they tell the boat crew or dm to keep an eye out, or they send an extra dm out, or they tell the diver they need to pay for their own dm.Many new divers recognize they are shaky or they are still afraid and they hire a private dm. They want the extra saftey. So maybe there needs to be 2 classes of ow certificates- class a that shows they are totally independant, and class b that says they are still shaky and require supervision.The dive shops could cater their dives to the 2 classes of divers, and I suspect would charge more for class b. I think many people who dive a few times a year on a cruise would choose to classify themselves as a class b diver and would like the security of knowing they are diving with a more supervised group. To become a class "a" ow diver you would have to pass more stringent tests.
This is just a thought anyway.
I think you make a good point, however, this is supposed to be the difference between an Open Water diver and a Discover Scuba Diving diver. The former should be capable of planning and executing their own dives safely, while the latter requires supervision.
You could also make the case that OW divers should require supervision, and Advanced Open Water divers should be capable of planning and executing their own dives safely. Although I think there are AOW divers that slip through the cracks of the system and are not advanced at all.
At some point we have to stop downgrading the classes and fixing the training. Unfortunately, I fall into InTheDrink's assessment of the situation, I can rant about it, but don't offer much in the way of a solution.