It's probably initially to do with the fact we're in charge of a huge machine which has the potential to harm others; it'd be just idiocy to allow everyone to operate one of these without them having at least basic profiency in the operation of the darn thing.
That's what your license is for, in part - it's proof that you've shown you're able to operate the machine with some level of competency.
To me, that's just common sense.
Driving is indeed a privelege, for the same reason. It's not a right. You don't have any inherent right to use a motorised vehicle on private
property, public property or anything inbetween, really. I'm not sure why you'd expect that right?
Frankly, I don't want licensing to be taken away. I'd be frankly horrified at the notion of some idiot who can't operate his way out of
bed, let alone a machine, being legally allowed to get behind a wheel and cause all manner of mayhem.
But that's just me.
As for road laws, most of these are also based on common sense...and that's largely because we are very obviously unable to act like reasonable
humans when it comes to driving
(road rage sound familiar?)
(how about the idiots cutting you off on the highway?)
(that's why we have laws. It's to protect the rest of us from the idiots)