I'm curious, what do you use plan9 for?
If you thought Unix was good, the question should be "why don't you use plan9?"
As for me, I'm a humble coder, so I use the tools I find best for that job.
Because I don't control the technical infrastructure of my employer or my employers customers and plan9 is not trivially compatible with that infrastructure.
... Which is why people are interested in what other people are doing with it.
Anyway, one thing I can add is that it is my screenshot on the Acme wikipedia page
http://en.wikipedia.org/wiki/Acme_(text_editor)
It has my plumbing rules for editing my php website