All because a person has some beef with a person and doesn't see them on the nicklist?
All what? All you said have anything to do with the suggested feature. It's only /ignore with the ability of not SEEING the nick in the NICKLIST. This doesn't mean mIRC would ignore it in the IAL, or that it should not /whois it. I don't get how could you think of these arguments, since /ignore doesn't do anything like that anyway. All these situations would stay the same. What about the pointless addresses argument? The user will deal with the format (s)he uses, just like we currently do. Now I repeat, all what? All nothing. It's a damn minor change which you could just not use, like I don't use a lot of things already.
About judging reasons for using this feature? I'd say
get over it, it's only being suggested. No one here must explain why would it be used, and you're not entitled to judge its usage this way you're doing.