[Raynor]

I would say that the best explanation for the treatment of the orcs is that the prevalent idea of their nature that Tolkien entertained during the writting of LotR is that they have no fea, and thus are mere beasts. The article Orcs from Myths Transformed is dated about 1959, although, true enough, in 1954 he considered them, in a letter to Peter Hastings, as a race of rational incarnate. Also, first-generation orcs, who were humans and became corrupted, would have a fea, unless being an orc means a separation of fea and hroa... Well, I know this theory has holes in it, but I think that it can best explain their treatment in the LotR.