Here's a defense of the increasing use of C# in Unity's low-level systems (not just for adding game logic on top of a C++ engine): http://lucasmeijer.com/posts/cpp_unity/ ...thoughts?

“I can easily see the machine code that is generated for all architectures as I change my code.” That’s quite the feature request. I wonder if a language that consistently outputs the expected machine code could be all that much better than assembly or something like LLVM IR?

effectively what they have there is not C# anymore, it just borrows C#'s tooling to create what is more like a shader language than C#. Since C# has very good tooling, I'd say that is a very valid decision 🙂