Well, wouldn't it be great if I were proficient in Blender, 3D Max, and Maya? Then I could create a mod.

Added 1 minute ago

I'm afraid not. It's a lot of work, with tons of imports and bindings... I can't even imagine who could do that. Although, I saw Uruk-hai somewhere...

Seriously? I recently tried to find this mod, but Google and Yandex only show mods for Skyrim.

Added 16 hours 6 minutes ago
Although, we could create a large "pack of neutral creatures from LotR" and replace all the races. It's not feasible to replace everything (except perhaps Mordor, Angmar, and Eriador (former territories of Arnor, just for reference)). The reason: creatures from level 1 to 7, and the armies of Gondor, Rohan, Erebor, and Isengard are not that diverse.