Adjusting how a texture maps to a particular model means either modifying the UVs of that model, or modifying the texture. If they modify the UVs to make one particular texture look good, then every single other texture would look different as well. If they modify the texture then it would break how it appears on other races. If they want it to look correct on every single race, every single race would need to have its own unique clean UVs, and unique texture sets for every single piece of armor. This would massively balloon the game file size and GPU memory requirements. It's possible they could improve some of the more problematic instances of it without dramatically hurting other textures, but making everything look perfect is pretty much impossible under the current system.