The really question is not "Why Use Perl", but "Why none is using Perl Here?"
Well, i've developed a lot of think in Perl (mirror checking, testing tools...) and also in a lot of other language.
All language is good for something, simply the Perl is good for more thing than other.
CPan say you: "Why use Bash Scripting?"
The supreme RegExp say you "Why Use python?"
I could go ahead, but Perl doesn't need presentation (oh well not here ;-).
I found two introduce Perl:
1_ Replace something (for example in testing tool).
2_ Do something new.
You must pay attention that 1 must be done (the first time) in spare time, because you can't (oh well i can't) say to manager:
"This morning i've rewritten ..."
because they will say
"ok, fine.... WHEN? During your coffe break, i hope!!!"
Perl is extreme powerfull, but also intertia is...
In my experience (dev/sysadm for a research group) the best way to introduce Perl is to find new needs, and resolve these with Perl... Every place is different, but if you find a problem and resolve it in Perl, Perl will become (in manager mind) the solution for a problem. If you rewritten a script in Perl it will become only An alternative to XXX