Personally, i'm very glad to see performance considerations being taken seriously, and even if nginx or node.js don't take over the world, its nice to see that they're forcing others to sit up and think.
Apache is "good enough" for most people.
NGINX or Node.js really don't bring much new to the table of "good enough".
It's why plan 9 isn't as popular as it probably should be. UNIX was good enough.
Just reading an nginx.conf and comparing it to an httpd.conf should be enough to convince you what nginx brings to the table.
The mandatory configuration is actually pretty minimal, especially if you are using it as an app server. Take, for example, http://kasparov.skife.org/blog/src/wombat/httpd-conf-cool.ht... which sets up a bunch of mod_wombat (precurser to now-bundled mod_lua) stuff.
On the high end, provisioning is fully automated.
Not to mention the fact that after > 15 years(!), amateur sysadmins like me can pretty much dream the config settings.
Which leaves a relatively small target audience for whom a simpler config is even remotely relevant.
And why should these five lines be buried in a 5000 line conf file?
The average user only ever has to access one small file with 10-15 lines.
There has never been a concerted effort to move Plan 9 beyond its roots as a research platform. The real world doesn't run on research platforms, and those of us trying to get real work done aren't going to invest our time in a research platform that needs enormous work to bring it up to a usable state.
You certainly didn't use nginx before it had any english documentation then.
The Mapnik GIS software (and the stack around it) used to be similar: a total pain in the ass to compile and configure, but people used it anyway because it was the best thing out there.
Mind you, I think these are real exceptions, and don't agree with the implied idea that good software will thrive regardless of how hard it is to work with.
Nobody has put effort into Plan 9's usability (which, by the way, is a much bigger problem than documentation issues), which was my whole point.