The thing most people don't realize is the actual creators of such 'cracks', exploits, etc. are not doing it for the destructive value of the creation (at least not in all cases), but the technical challenge it presents. I'm not commenting on the morality of that, but it is something similar to how a scientist could get a real kick out of working toward building an atomic weapon, not focussing on the terror it creates when it is used.
If khaled banned a network from mIRC usage, at least for this reason, he'd have to ban a lot of them. Plus, this would just give the people who write the keygens another challenge... to connect to banned servers.
Finally, I think it is important to note that this is a similar problem in many areas (some even outside the realm of computers). RIAA vs. MP3, MPAA vs. DeCSS, cops vs. robbers, encrypted/secure vs. crowbars and brute force.
It might be a good move if we all could come to some sort of compromise?