[Elladan and Elrohir]

Well, and I think you've hit the nail on the head there, alatar. The "heroes" do become perfectly pointless as the Dead rampage. Perhaps PJ could have made the Dead a bit smaller (as an army, I mean) and more like the Nazgul -- primarily wielding terror rather than physical power. Then they could have run off a section of Sauron's forces, leaving the main force still to deal with, thus calling for the continued heroics of Rohirrim, Aragorn, pretty elf-boy and belching dwarf, etc.