sed, awk etc are themselves rather complex languages (if not as complex as Julia). AFAIK their main advantage is speed, availability, and familiarity (where applicable, if you already use these tools).
But for my own purposes, Julia is already available, it is fast, and I am familiar with it. Also, for complex operations, it has the advantage that I can modularize my code and unit test parts. I find this crucial, and this is why I am not that keen on doing complex things with command line tools.