Correction: Most bash scripts are brittle. You can write rock-solid bash scripts if you know what you're doing. For example, Arch Linux is an entire distribution built mostly on bash scripts.
Of course, if your scripts only run on your own machine (which is a huge if), then fish is probably better.
Sure you probably can write non-brittle bash script, but it has always seemed above my own ability.
Beyond bash ubiquity, I've never found to have any other value against other slightly higher language whether it is perl, tcl, python, etc ...