Absolutely, but the idea here is a bit different. JavaScript is a language that we're stuck with for the entire foreseeable future of the web, for better or for worse ... and CoffeeScript is a conscious attempt to try and work within that limitation. Unless you're willing to take the significant performance hit of running an interpreter on top of JavaScript, you have to stick fairly close to JavaScript semantics.

That said, we certainly try to improve upon JS semantics, where it's possible to do so without a performance hit. Things like auto-lexical scoping, bound functions, chained comparisons and, most importantly, "everything is an expression", are all examples of this.