Y'know, I honestly don't care all that much if normal people can screw up: learning not to screw up should be part of the public school education all our taxes pay for. We trust normal people not to stab themselves in the eye, not to shoot themselves through the head, not to crash their cars into others: we should trust them not to do stupid stuff on their computing devices.

And when they do, we should hold them liable for any damage their actions have caused to others, just as we do with all those other tools. Yes, I think liability for allowing one's computer to become part of a botnet is a Good Idea™. Car crashes aren't accidents, and allowing one's computer to become infected isn't accidental either.