The problem with even minor skin modifications is twofold; first, Civitar and I do not delve much into custom art except for occasional color/shade transformations because that is a whole new arena (using advanced Blender/3DS techniques). We use existing art and suit it to the tastes of the unit. I was able to get away with making Orcs look unique because I layered new meshes over them (two different styles of plate armor, for example) or I completely changed the skin color altogether. Apart from that, every orc unit uses the same basic three meshes: loincloth, leather, or chain. I spent a lot of time doing the progressions so they wouldn't look similar, but was fortunate to have a lot of source material at my disposal - and a lot of time.
Second, Civitar's comment about separate civ's using the same units holds true - without Teamcolor, they will all look the same in-game. Teamcolor is the solution for this but it is somewhat daunting and problematic; I still haven't figured it out and Civitar is presently struggling with it as well. So, in the interim, my solution is to create new Orc color skins (I will do this for Goblins eventually also).
I am sure that both of us will eventually overcome the limitations that you describe. For now, I am just happy that we have Dwarves and other fantasy units to use; this was unprecedented for CiV until a few months ago! Thanks for your critique, we appreciate it and will hopefully address some of these shortcomings in due time

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