[tomp]

Null: Null is not evil, but programmers often fail to take it into account. If you see type `string`, it might not be immediately obvious that you can get either a `string` object, or `null`. It could be useful (for preventing bugs and for speed) to have different annotations for nullable and non-nullable variables/parameters (e.g. `string?`, or `string | null`, or `union(string, null)`).

Global GC: It's hard to do GC without stopping the world. If different threads have different heaps, only a single thread needs to be stopped at any given time for the GC to be performed (on this thread's heap). AFAIK, Rust also supports manually managed references.

Shared mutable state: I believe that is more of a language restriction, not VM (i.e. sending messages could be implemented without copying). Simplifies debugging and makes some abstractions much easier (distributed computing in particular).