In reply to felt: its idiotic and one suspects driven by the 'legalise everything' campaign. I suspect the costs of commissioning an intensive analysis such as proposed would cost more than we pay in dealing with the problem.
I hope MPs have much more important things to spend our money and their time on than crack heads wanting a free ride at our expense.
Its too simplistic to say that because we cannot eliminate a problem our strategy is a failure, you could apply that to any crime and just give up and let the anarchists have their way.