I intentionally use it as a sanity check; if the task exceeds POSIX sh, it's time to pull out Python (for me; substitute your "real" language of choice).
This is a good heuristic for advanced logic, but not when the main purpose of the script is to encode a workflow of coding other tools. I’m using other languages for that too, but shell scripting languages are consistently superior to all of them (including Perl and Ruby, IMHO; workflow languages might help but pull in tons of dependencies).
