You may have a point. I couldnt deny that they look a little mestizo, but they definately look more mediterranean. Greek, Roman, Spanish, Pheonecian, whathave you. Also, they definately lack the indigenous American appearance that would aid your mestizo theory.
Actually upon looking at them again. I would say there is very little mestizo in them. Most mexicans I know dont look anything like that, and I know a lot of mexicans (granted, there are other mestizos, but). I do however know a few greeks that could easily resemble them.
They look quite Mediterranean, I suppose. The only thing is that they are veeery dark skinned (when I look at them, they remind me to Romani people). I would like them to have more angled faces, more... Roman-esque, you know. More like http://romanencyclopedia.wikispaces.com/file/view/caesar.gif.gif/31752737/caesar.gif.gif.
Why not? They oh-so-obviously did this to appeal to America's growing Hispanic population. In the Imperial presets, you can see Johnny Depp(Part Cherokee), "Machete"(Dammy Trejo), etc.
You know that Cherokees have nothing to do with Hispanic people, right?
About the topic, I like Imperials for my knights, but first I'll play as a Nord warrior. Then, a Nord bard... and later, or at the same time, a Breton battlemage (my favorite one).