Why doesn't C# have exception specifications?

C# Exception Specs

Why doesn't C# have exception specifications?
Some languages allow or require member signatures to include exception specifications. For example, in a language with such a construct, a method that raises an ArgumentException can be declared with:

void DoSomething(int a) throws ArgumentException {...}


C# neither requires nor allows such exception specifications. There are a number of reasons for this omission, namely:

Versioning
Productivity and code quality
Impracticality of having class author differentiate between "checked" and "unchecked" exceptions
Difficulty of determining the correct exceptions for interfaces.