Your points about the orcs and goblins are valid. But looking at it from a story telling point of view, or even from the point of view of the characters, where the only interaction with the creatures is danger. The point of view of a hobbit viewing a group of Orc's the hobbit would not likely be pricy to the campfire conversation and music of those hunting him as dogs hunt rabbits.

In the Star Trek universe Klingons started out universally bad until further development made them admirable allies, at which time they were replaced as evil antagonists by Cardassians and Borg.

Getting back to point of view and the war you brought up, If the Japanese Islanders had seen the invading Marines as people like themselves would they have flung themselves and their children off cliffs rather than surrender? Were not the concentration camp guards who committed mass murder worse than any creature in a LOTR book? Gassing people, making lampshades of them? But yet they had mothers wives and children and probably drank beer and ate sausage in October.

I don't think the LOTR movies need sympathetic orcs anymore than a movies including Gestapo and SS troops need scenes of baby NAZIs eating black forest cake with their moms.