Actually, they do write this, and nobody cares. Unfortunately, rather than treating these injuries as the evidence of child neglect that they are, the feds have taken the approach of banning something that, when used appropriately, is perfectly safe.
The problem is that they are a harmless-looking toy, but the only safe way to use them is to make sure no small children are present, take them out and play with them, then count them to make sure none have been lost, and lock them up. If someone loses two of them, then children are in grave danger.
As for child neglect, if you were visiting someone with your small child and a teenager was playing with a bunch of magnets, would you immediately think "those are very dangerous, I must keep my child on my lap so that he doesn't pick one of those up"? Of course not. Since you have not seen the package, you have no way of knowing that these particular magnets are much more dangerous than those which you played with as a child.
This does not mean that everything sold has to be safe for children. Guns, knives, fireworks, blowtorches, and chainsaws are dangerous by the very nature of what they are intended to do. Even small children immediately understand their capacity to destroy things. The CPSC does not ban chainsaws because they cut or blowtorches because they burn. But it does ban toys when they tend to cause harm in totaly unexpected ways.