> Or you might have a load of methods that actually throw 'Not Implemented' errors because you are forced to match a massive interface but it only has to do one thing ... The other thing is that you're sometimes forced to cast a variable to a type that you know is already that type, but a method has returned it as an 'object'. It feels really clunky

These are not "problems with static typing", though. Dynamically-typed languages have you do these things all the time, it's just that you don't even notice it anymore because it's so common and you don't have static types as an alternative there.