[catnaroek]

Most likely the reason is keeping the language implementation simple. Java-style `null` is actually quite subtle: http://stackoverflow.com/a/2707333/46571

[pcwalton]

Go has the same complexity. From the Go spec: "For an expression x of interface type and a type T, the primary expression x.(T) asserts that x is not nil and that the value stored in x is of type T.'"