Seems to hit it right on the nose. I write JavaScript for a living and can say that each of these skills is fundamental to my success. Good read.
If you're a solo developer writing small applications, this might not be a problem. If you're growing an application and a business this is a very serious concern. As you grow, you need to bring in more developers, but with a cowboy codebase it will be harder and harder to keep everyone productive. Instead of writing new features, they'll spend more and more time just trying to undersand the code, and to fix the inevitable bugs.
Quick fixes are a fact of life though, but use them only until a solid patch can be crafted.
A few more: What are dangers of using prototype inheritance with many instances of that class (meaning accidentally attaching variables to the prototype rather than the instance)?
What are some gotchas with IE < 9 event objects in event handlers that contain closures?
Explain the same origin policy, why it's important, and how it impacts your development.
(jQuery twister): explain where the '$' variable is defined when used with jQuery. How might you manipulate the DOM in another popup window you've created?