Take my use-case: I get random-ish formated data through email and need to often create semi one-time python scripts that do specific jobs with that data. That mean I need to clean the data and separate relevant from irrelevant, format it to be used with python, last take the output and format that as requested.

Macros are invaluable. Search and replace regexp is invaluable. Compare buffer, unique, sort and rectangular insert is invaluable.

There is no purpose-built python IDE that is tailored to my use case. The closest is ipython, and I already run that parallel with emacs when doing more complex python coding.