[cyorir]

As far as why Plan 9 didn't break the status quo, I'll have to agree with what Eric Raymond said in 2003[0]: Plan 9 was not "compelling enough," whereas Unix was "good enough."

In my own opinion, a sufficient number of people, projects, and services were already using Unix-based systems, and they had constructed their projects and services around this Unix model. The marginal benefits of Plan 9 were not great enough to offer sufficient incentive to deviate from the Unix model.

[0] http://catb.org/~esr/writings/taoup/html/plan9.html

[EdiX]

ESR is wrong on this point. Not completely wrong, I can imagine a world where things went differently and his assessment was correct but it's not the world we live in. Plan 9 "failed" because it spent almost 2 decades between "almost impossible to license" and "almost unmaintained". AT&T was more concerned with preventing anyone but them from making money off of Plan 9 than they were concerned with actually making money off of Plan 9. Lucent only got it long after the ship had already sailed, they don't seem to know what to do with it, it's commendable (and surprising) that they did not just gun it down.