But does it work having an enemy that is not 'pure evil' when they are slaughtered on a massive scale? And does it actually make them frightening? The main way Orcs scare us is by sheer force of numbers against the good guys who we love, or even against slightly infuriating heroes like those we see in the Sil (as opposed to the more 'shiny' figures in LotR - but there's another thread in that one
).
Would it be better if Orcs were incapable of being redeemed? I think they would be much more frightening.