Go to google maps and zoom out, urban sprawl is not the problem. You are talking about ending a way of life that untold millions aspire too, I wonder what kind of affect that would have.
That said, I do think banning them (even just by developers) is unnecessary if you provide zoning incentives instead. If you give developers the option to split up land because it will give them a higher return, they're typically quite quick to do that, at least in Australia. That wouldn't prevent owners or speculators from building their dream standalone house.