Actually the addition of the neutral to save people from their own stupidity was secondary.
What actually started the proposal was the decision of some manufacturers to make a switch that required power to operate and then decided that the way to sell even more of them was to use the hot and ground to power the switch. This put 'objectionable current' on the grounding conductor which the Code doesn't allow...but the manufacturers refused to withdraw or modify their product so the rule was passed to accomodate their poor product design.
Once again one bad apple ruined it for everyone.
Thanks a lot to the marketing guys at the *** company.
