Its the Subversion of the Innocent.
On a primal level, we both want to and detest it. Teaching a parrot to swear is fun and cute. (Same thing with a kid. Somebody else's, never your own. That's just bad parenting.)
But using a children's toy to murder and kill? That's like putting a razor blade in Halloween candy. It ruins things for the kids, not the parents. You're taking away one of the last bits of innocence that children have.
We're Shadowrunner's, damnit! We're supposed to be the good guys, and you want to take toys away from kids? Drekheads.