They're easily recognizeable because they were in the movies. I hardly think that's a valid reason to include them. I mean, do you want an insta-win army of the dead that effortlessly buttrapes the combined hosts of Minas Morgul, the Southrons and the Easterlings, even though their actual role in the books was just to get rid of the Corsairs of Umbar so that the armies of Lebennin would be free to come to the aid of Minas Tirith?
Note: If you answered yes, you're irrelevant.