Would it not be possible to leave a wiki like redirection, so anyone going to the old pages is redirected to the new?

Sure it would be possible, but its not sensible

Newbees aren't confused because "PerlMonks Discussions" to them sounds like "I want to ask a question here"

Newbees are confused because there is no prominent ask new question here button/link , so they use the first form they stumble upon

Now if the link in the navbar needs improvement, well then you simply change the text of the link (Site Bugs ), you don't change what it links to ( PerlMonks Discussion ), as its had that name for 17 years

But like I said, the problem isn't the name of pmdiscuss, the problem is lack of new question button, an old and well known problem, but the gods dont think its needed, so situation remains stupid :)

Maybe you bold the Seekers of Perl Wisdom link in the navbar and make it <blink>Seekers of Perl Wisdom</blink>