First off, it's not installed everywhere. That adds a huge barrier to use right there. I don't feel like downloading and compiling new software for every machine I use, especially not when I am not root. I'm sure it's good, but it doesn't save Unix from sucking because it's not part of the system most of the time.
And really, the last thing I need is to sit around trying to remember how to write cryptic statements like that. "esac"? Double semicolons? "*.jpg)"? This is just more o the stuff we already discussed how utterly badly it sucks.