Voice is not determined by how you look or act...
That said, there are ten races of two genders. This means they already need to record potentially twenty sets of vocalizations for the player character. For each option you add you add twenty more sets. I don't think it's realistic to add much variety.
Well, I started with Oblivion as opposed to any of the other games, and all the racesl sounded more or less human to me, so I figured they could just have a male and female voice. However, I have seen threads with people wishing the non human characters returned to sounding more beast like (which I'm unfamiliar with considering my only Elderscrolls experience is with Oblivion). So I understand the reservations (more like adament dismissals really) especially having thought more about it. I still would prefer it though in hopes that the actor/actress used sounded good in the role, but I get, I get it... I'm the only one and that's fine. It'll either happen or it won't, and it probably won't since it seems an unpopular idea and I'm fine with that. I will play this game and most probably love it regardless since it seems to be fixing every problem I had with Oblivion and more (emphasis on the "MORE"). I can't wait... seriously!