Why Perl?

...
Perl supports objects and modules. You can define classes, with member functions, and use them just like C++: reference->MemberFunction(5).
Perl does memory management for you.
Perl goes through a compile phase and a run phase, so many errors are caught in the compile phase, before the script runs for the first time.

Now, it's not a perfect language, so here are the bad points:

Perl is 450k of code. Between loading Perl (0.15 sec on a Sparc 5) and loading the script (0.1 sec for 400 lines), the startup time is not entirely negligable.
Perl isn't nearly as fast as C or C++. Complex calculations may be too slow.
Some errors are caught at run time, so scripts will sometimes misbehave long after you thought they were debugged.