Is JavaScript's “new” keyword considered harmful?

Question

In another question, a user pointed out that the new keyword was dangerous to use and proposed a solution to object creation that did not use new.

Answer 1

Case 1: new isn't required and should be avoided

var str = new String('asd');  // type: object
var str = String('asd');      // type: string

var num = new Number(12);     // type: object
var num = Number(12);         // type: number

Case 2: new is required, otherwise you'll get an error

new Date().getFullYear();     // correct, returns the current year, i.e. 2010
Date().getFullYear();         // invalid, returns an error