Why can't we access enum values from an enum instance in C#?

This might get downvoted, but this question has been bothering me since yesterday.. until I found a link then I knew I wasn't really crazy lol: Enum as instance variables

I'm basically asking the opposite of the OP's question. Given:

enum Coffee {
    BIG,
    SMALL }

public class MyClass {
    private Coffee coffee;

    // Constructor etc.
}

Although this is Java and enums do differ somewhat in both languages how is it that I can't do coffee.BIG or coffee.BIG.SMALL (though it makes little sense when reading it, it should be possible considering coffee is of type Coffee) in C#?