Nobody but other devs cares about the simplicity of the code if the code works.
>The code and hosting requirements are, frankly, Frankenstein's monster levels of frightening.
Huh? Wordpress/PHP hosting requirements are the easiest to meet in the industry. Not to mention the most widely available...
>~~You have to~~ WP expect you to install it such that it can modify its install folders - all of them. Security-fucking-nightmare.
Yeah, so? It's self-updatable. Use a dedicated user/group.
>It falls apart under any kind of load, both because of unoptimized DB queries, and because of PHP.
Absolutely not "because of PHP". If anything PHP is faster than both Ruby and Python, two other common choices.
>You have to put a cache in front of it to be able to handle getting on HN, let alone Reddit.*
That's the case with most CMS, PHP or not.
>Arbitrary plugin installation, in a non-sandboxed environment (see prior point about an application-writable install).
It only happens if you chose to do it. Plugins don't magically install by themselves.
So it's not much different than any environment where you can download a jar, a python package, a ruby gem, etc and have them add functionality into the CMS.
>Need more be said?
More, no. Better, yes.