Just out of curiosity, how much experience do you have with full-featured IDEs? The reason Perl doesn't have much in the way of decent IDEs is that Perl really doesn't support them terribly well. It's introspective capabilities are really poor, it's very difficult to parse, you can't infer method or function signatures, the standard testing packages only allow primitive hooks and the debugger is a nightmare (though Devel-ebug seems like a step in the right direction).

For these and other reasons, IDEs for Perl tend to be limited in scope. A good IDE can speed development quite nicely at the cost of the programmer not memorizing many things quickly. Frankly, I don't want to need to memorize all of the methods DBI uses to fetch results, but instead I need to keep popping open perldoc to remember exactly what I want. A good IDE makes that available in a couple of keystrokes.

You might be happy with vim + shell + perldoc, but for many Perl developers, they have to be happy with that because that's all they have. It's almost like Guido suggesting closures aren't valuable because Python doesn't support 'em :) (yeah, that's a cheap and somewhat inaccurate shot)