No definitive answer from me, but here's my thoughts:
I drove fine at 15/16 (here, you can get a Learner's Permit at ~15), and to this day I've never been in an accident.
My brother, on the other hand, didn't get his license until he was 17 or 18, and he's been in one decently major accident, and a few minor ones.
Waiting until he was older didn't make him a better driver; getting my license younger didn't make me a worse one. Granted, I'm sure that someone else here can make the exact opposite statement. IMO it's completely individual.
That's an interesting thought, though, and there's plenty of reason to raise the age (as bacchus mentioned, there is a biological basis to it). People of that age demographic do have the highest crash rate-- though I have to wonder if it's because 16-to-18-year-olds are just worse drivers, or if that demographic has a comparatively higher crash rate because being a bad 16-to-18-year-old driver is what made them a better 19+-year-old driver. People do learn from experience, after all, and being in a crash (or near-crash) does tend to straighten out previously-careless drivers.
If you remove the 16-to-18-year-old drivers, would the (for example) 19-to-22-year-olds become the new "bad driver" demographic, since they're the new "new drivers"? Or would being older and (debatably) more mature balance the lack of experience? It's an interesting thought.
It's my general belief that minors are as responsible as they're taught to be. Something like this is pretty individualistic, but I don't think changing the age would make a huge difference to anything, in the long run.