However, WordPress is not cool so they went to the tired old "reinvent blogging". No open source contributions, just building castles in their own sandbox.
The opportunity cost from system migration (and re-invention) is non-trivial. But so are the opportunities gained with a new infrastructure. The speed gains from serving static files is nice, but to me, they are no where near the kind of gains I make by being able to work with plain text files.
When I want to write a file, I pop open my (probably already open) text editor, bang it out, save, switch to Terminal, push to S3. Did I make a typo? OK, fix the typo, save, re-run the Terminal command. Maybe I want to push a few posts, but I want to make sure they all look right...OK, run the jekyll server and look at localhost. Then run the push command. Oh wait, maybe one of those posts should be a draft. OK, set it to draft in the metadata, re-push, etc. etc.
I have a particularly bad experience with WordPress because I've been running my blog on it for five years on the cheapest Dreamhost shared server. However, I've spent a good amount of time researching and installing WordPress plugins to do caching...but the problem is that every goddamnned database action, including setting a post from draft to publish, or vice versa, is a 5 to 50 second process.
Obviously, Stack Exchange doesn't suffer under that kind of hosting issue. And they could probably set up their WordPress on a local instance so that it can be locally browsed (in my experience, this can be profoundly difficult, and quite the weekend project). But no matter what their hosting infrastructure is, it still doesn't negate the fact that every posting action requires a database -- everything from creating users, setting user roles, setting post status, and of course, editing the post.
Sure, you have to learn those things in Jekyll too...but the conventions are easy...and most importantly, you can do them within the confines of your text editor. That means everyone who contributes to the blog, engineers and marketers, gets better at their text editor (and operating system). This is a much more worthwhile skill than getting better at WordPress...which is a non-trivial skill...WordPress, to its credit, is fast moving in its development...for occasional publishers like me, this means I spent a good amount of cognitive energy re-learning the interface. With Jekyll, even as the software changes, I just have to learn my text editor. And that's just wonderful, considering how much of my work involves a text editor.
For non-techies, I imagine it's a little daunting at first...but they're fully-functioning adults. They can handle plain text. And working with Jekyll not only makes it easier for the engineers to do the occasional hacking of templates, it allows the non-techies to actually _see_ it without having to jump through the many plugin submenus in the WordPress admin. It is literally a Cmd-T (in Sublime Text) to look up a file. Or, a Find All across a project...which is another huge benefit...blog contributors often need to look up past material...the text editor search is far superior to what can be done in the WP Admin or other web search interfaces.
So it's not that "WordPress is not cool"...and the fact that you think that one solution is to "just fix WordPress" makes me think you don't understand the problem. WordPress doesn't need to be "fixed" to be more like Jekyll, it is a fundamentally different product, with certain tradeoffs and benefits worth pursing. To say that the OP should've "just fixed WordPress" is like saying, "Why use Facebook? Just get better at using the CC: field in email"
:)
