You are absolutely right, as I said it would not stop every problem but it stop many.

Consider this option.
mIRC assigns and ident of "F7C46543" and appends the same value at the end of the FULLNAME (non-editable).
If you have a real problem user, who is just abusinve but not technically savvy this could be easily used to verify the person as his WHOIS details would return contradicting values.

I'm not suggesting this is the solution but it could be, as it stands now ident is so irrelevant that any improvement on it becomes a major improvement.