In reality, there is always some idiot who who does something stupid and can't/won't handle his weapon in a safe and responsible manner and causes people to call for more laws.
Open, unloaded carry was, until recently, legal in this state and there were people who would deliberately carry in public just to get the police to respond so that they could argue with the police about their rights and make a scene.
That is both stupid and irresponsible in any situation, but considering recent history, it's a good way to get yourself shot, not to mention making gun owners in general look like a bunch of idiots.
So, personal responsibility cannot be relied on.
Like CC, I have no issue with a training course, with the caveat that it is not excessive in length or cost.
Those courses protect the rest of us because we can then show that if somebody did something stupid and/or illegal, they knew the law and they did whatever it was anyways.
As far as the slippery slope goes, again, in principle, I agree, but in reality, it doesn't matter.
There are a lot of people in this country who believe that a woman has a right to have an abortion and kill her child, but those same people believe that same woman has no right to carry a gun to defend her child.
As long as there are a significant number of people in this country with that view of the world, we are stuck on a slippery slope and the laws passed or blocked only vary how fast we slide down that slope.
If we can at least hold the line with reasonable (by responsible gun owner's standards) training requirements, then we slow the descent.