> Or why expose this interface {} feature and allow people to use it in a statically typed language?

`interface{}` isn't anything special, or something akin to `void*`. Interfaces are a core part of the language, and `interface{}` is just the literal form for an "interface with no methods", which happens to match anything since all types can fulfill an empty method set. It's no different than using this `Something` for exmaple:

    type Something interface {
    }