Why is `with` not recommended? Is there any better or other ways to "descend" into an object's namespace?

Question

From MDN:

Using with is not recommended, and is forbidden in ECMAScript 5 strict mode. The recommended alternative is to assign the object whose properties you want to access to a temporary variable.

It seems like a great/useful/convenient feature. Why is it frowned upon? What other ways are there to achieve that effect? I don't want to have to go:

veryLongNS.y = veryLongNS.myFunc(veryLongNS.x);
veryLongNS.z = 6;
veryLongNS.otherFunc();
veryLongNS.a = {
    a:1,
    b:2,
    c:veryLongNS.processThree(3)
};

Answer 1

Here's a related answer: Are there legitimate uses for JavaScript's "with" statement?

Also: http://yuiblog.com/blog/2006/04/11/with-statement-considered-harmful/

How about the following as an alternative?

(function(obj) {
    obj.y = obj.myFunc(obj.x);
    obj.z = 6;
    obj.otherFunc();
    obj.a = {a:1,b:2,c:obj.processThree(3)};
})(myAwkwardlyNamedObjectToBeUsedAsANameSpaceThatIWishToModifyAndNotJustRead);

Edit: For clarity and posterity, this is also possible (and in most cases would be preferred over the above -- I wouldn't recommend doing it in the global scope, but I wouldn't recommend doing anything in the global scope):

function someFunction() {
    // in some function
    var obj = myAwkwardlyNamedObjectToBeUsedAsANameSpaceThatIWishToModifyAndNotJustRead;
    obj.y = obj.myFunc(obj.x);
    obj.z = 6;
    obj.otherFunc();
    obj.a = {a:1,b:2,c:obj.processThree(3)};
    // ... any other stuff in the function
}