Rust is a relatively new (compared to e.g., C or Java), statically typed language. That brings some chances and challenges. When creating a new ecosystem from scratch, you don't have to keep any backward compatibility. It can be created based on lessons learned on other platforms introducing more radical changes.
Null's are a nightmare for a lot of languages. In Rust, you won't find them. Every case other languages handle using null is handled here by an Option enum. In Rust, all variables are immutable by default. Why? Let's answer with a quote: Immutable objects are always thread-safe. - Brian Goetz
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