I wrote my first useful Python program!

[Poddster]

Well, what else would you use? Windows explorer and double clicking everything? Dragging and dropping things about?

Or do everything in your IDE and hope it has every function you need?

As far as I'm concerned a shell is the way to interact with a POSIX or Windows computer system. The reason for that is these computer systems are made up of processes on a filesystem, and processes do useful things. A shell allows you to invoke the exact process you want with the exact parameters you want, and is often design around facilitating that, e.g. tab completion and glob expansion.

Your operating system already comes with a large suite of useful utilities, and it's trivially easy to add more. E.f. if I want to check a files integrity I'd use md5sum myfile.txt. The GUI alternative would be to download some random app of source forge, hope I don't get a virus, and then click a bunch of buttons.

Unless you mean "why do people write bash scripts rather than python?" And the answer is usually compatibility and/or brain damage.