Fundamentally, the primary requirement should be that one be able to pay for any damage one does. If one wants to post $150,000 collateral, fine. If one can convince an insurance company to insure one, fine. It's unlikely that an insurance company would want to ensure a driver who had not passed some sort of competency test, and it's unlikely that someone who could afford to post $150,000 collateral wouldn't want to seek out some training to minimize the risk of having to pay it out, but governments have abused their claim that transportation is a privilege rather than a right; while it may be politically tough to buck the trend, I'm glad some politician at least recognizes the issue.
If you made licenses optional, most insurance companies would probably require them in order to get a reasonable-cost policy.
The bigger problem would be that even those who might agree with this idea would probably also agree that, on causing an accident, one’s right to drive should be curtailed — and how would we do that if there wasn’t a license to take away.
Just hope they don’t start licensing cell phones, since they cause more accidents than most anything else, because people don’t apparently know how to use them (like NOT texting while driving, or not talking while walking across a street and getting run over). OK, I’m parodying the argument here.