I have one situation where bash + sed is preferable: embedded devices where storage is a primary cost component. Having a shell on the device is somewhat necessary for development. It so happens that the shell is also a decent language interpreter, so adding another interpreter doesn't always justify the cost.

I eventually got pretty good at doing both functional and OO-style programming (each where appropriate, and straight-up imperative scripts in many other places) in POSIX-compliant shell.