I think the biggest thing I miss the most when developing in other languages is the lack of built-in complex data structures. Want a hash? Instantiate a new one from the class library (which isn't always obvious since the names are different).
Try a simple HoAoH or something equally trivial for Perl in a language like C#. You'll be casting yourself to death just to get one of the bottom children elements. Think C# 2.0 will help you? Sure, you rid yourself of the headache of casting, but you have silly looking things like
Dictionary<string,List<Dictionary<string, MyObject>>> HoAoH = new Dict
How many angle brackets do YOU see?
I think people take built-in complex data structures for granted more than any other feature in Perl