There is a class of programs where manual control over memory layout is important. For example, if you're writing an OS, as Mozilla is, you need this control to talk to hardware. It is also important in some domains where performance is important (e.g. games and big data.) Rust is the only language (outside of research) that offers control over memory layout while also providing memory safety. That is, no access to uninitialized memory, etc. This clearly eliminates a huge class of bugs relative to C/C++, the only language with substantial usage in this space.

Race conditions (data races) are considered important enough by the Go developers that they have a tool to detect them: http://blog.golang.org/race-detector In Rust these error cannot happen as programs containing data races cannot compile.

Then there is the usual modern type system stuff of eliminating nulls and so on.