I don't see why a well written library could not serve the same purpose. It seems like a lot of cruft. I doubt, for example, Python would ever consider adding this and it's the defacto language that would benefit the most from something like this - due to the existing tools and communities.

It just seems so narrow and not at the same level of abstraction that languages typically sit at. I could see the language supporting higher level functionality so a library could do this without a bunch of extra work (such as by some reflection).