John Gruber is right: his four-year-old Daring Fireball essay, Ronco Spray-on Usability, still holds up nicely indeed.
Alas, the notion that usability is the easy part—something you just add on after doing the hard part of writing the code—is hardly limited to the open source community.
There are still many companies that think information architecture holds a mirror up to the org chart.
There are still many web clients who believe it is more important to support an “investment” in a moribund technical platform than to create great user experiences.
There are even (although there are far fewer than there used to be) some designers who think their primary job is to wow the user with their skills.