In my opinion, shell scripting is the right tool when you need to do a lot of calling programs, piping, and redirecting. Such programs end up being cumbersome in "proper" languages.
If there are already software written to do the stuff and I'm just coordinating them (no other computation other than string manipulation) I'd take bash every day. I would only reach to python if I need to do stuff like manipulating complex data structures or something with heavy logic.