I think proper type inference along with some sort of struct literal syntax could make a lot of these problems go away without the need for structural typing. If you can create structs without explicitly mentioning the type (as long as it can be inferred), then you can use the same syntax for different types as long as their signatures are the same. Structural typing makes it too easy to accidentally pass something that looks like a duck but is actually a goose.

As an example, this syntax should be possible without structural typing or explicitly specifying the type of the value:

    // assuming a type signature of moveToPoint(Point)
    moveToPoint({x: 5, y: 10}) // the struct literal is inferred to be a Point

I believe F# has syntax like this, but it's been a while since I've used it so I don't remember the details.