Sure, but the big problem with a static structure is that once you are down the road the inevitable 'unknown unknowns' creep in, no matter how tastefully you've designed your interfaces (whether they are literally java/c#/etc. interface types, or class definitions, hierarchies, etc.), and it becomes incredibly difficult to modify things without there being a lot of work involved in fixing things up.

I really do think go's 'real interfaces' i.e. types being implicitly convertible to interfaces which have matching method sigs is a tasteful stroke of brilliance, especially for a lowish level language.