I feel like this kind of makes my case for me: Buckyballs was marketing a desk toy that turns out epidemiologically to be more dangerous to children than leaving a chemistry set unattended on a desk.
I'll also make the further point that chemistry sets aren't actually that dangerous (and never were). 'More dangerous than chemistry sets' is a largely meaningless statistic.
As an aside, I don't see much effective difference between a legal crackdown and one caused by fixing the social context.
'Some degree of danger reduction' just doesn't qualify as a catch-all justification for regulatory action. At least not with me.
And in the magnet case, larger magnets are plenty fun while still being much safer.