See Bashing the Bash — Replacing Shell Scripts with Python for some concrete examples of stuff you can do in Python or the shell.
And yes, it's a good, workable idea.
- It's unit testable.
- It's easier to read.
- It may be faster. Not that you'd notice unless you've really made a terrible mistake and written some gigantic application as a shell script.
While you're at it, check out the overall blog: https://medium.com/capital-one-tech. There's a lot going on.