I was tempted to cite Antoine de Saint-Exupéry's quote on perfection, but we all know that, right?
But then again, even the author mentions at the beginning the "risk of adding too much" and, well, I wonder if this has not already happened to JavaScript.
JS is a language where new features can only be added by changing the language itself. There are other languages where new features can be implemented as third-party libraries. This allows people to experiment with new approaches to problems, try out new features and test them in real world. Once the community agrees on their usefulness, they are integrated into the standard library so everyone can profit. These are languages where you can't really remove that much, from the language itself. And any new language features (changes to the core language itself) are driven by "what is the minimum change we need to do to allow third-party code to grow even better" rather than … well, whatever that thing is that the JavaScript community is doing.
But then again, even the author mentions at the beginning the "risk of adding too much" and, well, I wonder if this has not already happened to JavaScript.