I've been doing a lot of work with javascript recently and it's really hard when you have a lot of code. Javascript needs tools like this if it's to go beyond being a web site helper. TypeScript is C++ to javascript's C. There are many similarities. Early C++ compliers were preprocessors that output C. The main problem with CoffeeScript and the like, is that you write CoffeeScript but debug javascript. The big step is being able to debug in the language you wrote the application in and that's when it moves into mainstream development. TypeScript isn't there yet but I bet it won't be long.

If you like coding in C then great but if all we had was C then building today's apps would be a monumental task. I for one think this is just the first step on the road and getting the likes of Microsoft involved must be good.