Interoperability with C is one of their main points, so it's logical they want to focus on that. Even more, the success of today's language is also being measured how well it behaves with existing codebase. It will be more true in the future, because the existing source code only grows.

Well, maybe the last bit isn't true for webdev, where if the code rots it's simply being deleted. Web applications, if they're taken off production, they're nowhere to be seen, most people never realizing they ever existed, but even if they knew those applications existed at some point in time, they would never be able to even see how they looked like.