[pdonis]

it's not clear what real benefit Tor provides us in exchange for letting this kind of activity go on

How about letting people in countries like Iran and China have a fighting chance of getting the word out about what's really going on there? Does that count?

How about letting people who are being stalked by creepy ex-spouses or ex-significant others have a chance of doing things online without being tracked? Does that count?

How about letting people who are afraid of reprisals speak inconvenient truths without being silenced? Does that count?

Basically you are saying these kinds of benefits aren't worth the chance of letting someone distribute child porn using Tor. That seems ridiculous to me.