I think that what your proposing is a bit like saying you must have a full articulated truck licence before you can first take to the roads.
Aside from the huge cost, having that truck licence will not necessarily make them a safer driver initially. Yet because they have that truck licence, they are qualified to take a 40 tonne truck to the road with no experience. I think THAT is dangerous!
"The biggest failing in aviation is the pilot", I couldn't agree more. Not only their skill level, but their decision making.
I think that initial pilot training should focus far more on good command decision making and risk assessment. We spend all this time making sure they can do an auto for example, for a situation which statistically is very rare, yet every hour they fly they must make decisions to ensure the safety of the aircraft.
A night rating will not be required if the pilot makes sound decisions to ensure they do not get in the situation where they need one. Same for an instrument rating. They are not going to spud into the side of that hill if they are not pushing weather they shouldn't be.
It is important that they are aware of their limitations. If you throw every qualification under the sun at them and send them on their way thinking they can do anything, surely that would reduce that awareness and create an environment for over confidence?
A good saying I once heard: "It is dangerous when they don't know what they don't know."
I personally think a far greater gain to safety would come from more training on an awareness of their limitations, and to identify the risks associated with things such as:
Pushing bad weather
Commercial pressures
Fatigue (often from commercial pressure)
Over confidence (that soon replaces the initial lack of confidence)
Complacency
etc.
Rather than over qualifying an inexperienced pilot.
Send them out with a limited licence AND and an awareness of their personal limitations first.
You've got to walk before you can run.