mIRC is very similar in nature to MS Outlook. What I mean by this? It is very good for the primary function it was designed for (chatting and e-mail respectively), It also comes with powerful scripting and thus it is exploitable and used to pass on viruses.

What if DCC send/receive would work only if both sides had each other in the address book set by default to ON?

What if the firewall support would only work if the firewall was on the same IP range (depending on class A B C) or on the same domain if the name was resolvable? After all, the feature is called "firewall" it is only meant to get you trough your local firewall, and not for exploiting other connections.

What if mIRC used some serial number as ident? After all you are not doing anything wrong thus you don't get banned right?
And no, serial numbers do not affect your privacy any more than any other information in nickname/ident/fullname. Perhaps this feature could be turned on by 005 numeric, at the network's request (REQUESTMIRCIDENT=YES).

What if mIRC would allow you to set a password to protect your scripts from being modified, perhaps using MD5 values for the scripts? The same feature would also mean you cannot load

What if I stop for now, LOL.