Brat general reply: while many valid points have been made, legit users would also be "punished" by any limitations made in mIRC. Not so legit users would find a way around them *grumble* I tend to agree with those who suggest networks need to take a bigger stand on file sharing channels/bots that exist just to fileshare. Many providers are taking steps to limit filesharing, that also helps.
How exactly would legitimate users be punished if some DCC features were disabled in illegal copies of mIRC? If you have such a copy, then you are not a legitimate user therefore it is someone who is breaking mIRC's license that is being punished, not "law abiding citizens".